Method for performing detection by node in wireless communication system and node using same method

ABSTRACT

Proposed is a method for performing detection by a first node in a wireless communication system. The method comprises: receiving detection configuration information from a second node; and when detection request information is received from the second node, transmitting a detection signal to a neighboring node on the basis of the detection configuration information, wherein the detection signal is aperiodically transmitted and is transmitted on the basis of beam sweeping.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of International Application No.PCT/KR2019/006266, filed on May 24, 2019, which claims the benefit ofearlier filing date and right of priority to Korean Patent ApplicationNo. 10-2018-0059334 filed on May 25, 2018, No. 10-2018-0087673 filed onJul. 27, 2018, and No. 10-2018-0094053 filed on Aug. 10, 2018, thecontents of which are all hereby incorporated by reference herein intheir entirety.

BACKGROUNDS Field of the Description

The disclosure relates to wireless communication and, more particularly,to a detection method performed by a node in a wireless communicationsystem and a node using the same.

Related Art

As a growing number of communication devices require highercommunication capacity, there is a need for advanced mobile broadbandcommunication as compared to existing radio access technology (RAT).Massive machine-type communication (MTC), which provides a variety ofservices anytime and anywhere by connecting a plurality of devices and aplurality of objects, is also one major issue to be considered innext-generation communication. In addition, designs for communicationsystems considering services or user equipments (UEs) sensitive toreliability and latency are under discussion. Introduction ofnext-generation RAT considering enhanced mobile broadband communication,massive MTC, and ultra-reliable and low-latency communication (URLLC) isunder discussion. In the disclosure, for convenience of description,this technology may be referred to as new RAT or new radio (NR).

One potential technology intended to enable future cellular networkdeployment scenarios and applications is supporting a wireless backhauland a relay link, which enables a flexible and highly dense deploymentof NR cells without needing to proportionally densify a transportnetwork. It allows for flexible and very dense deployment.

With massive MIMO or a native deployment of multi-beam system, a greaterbandwidth (e.g., mmWave spectrum) is expected to be available in NR thanin LTE, and thus occasions for the development and deployment ofintegrated access and backhaul links arise. This allows an easydeployment of a dense network of self-backhauled NR cells in anintegrated manner by establishing a plurality of control and datachannels/procedures defined to provide connection or access to UEs.

For this next-generation scenario, a method for an IAB node to detectand measure another IAB node that is different from a conventionalLT-based detection and measurement operation is required.

SUMMARY

An aspect of the disclosure is to provide a detection method performedby a node in a wireless communication system and a node using the same.

In one aspect, detection method performed by a first node in a wirelesscommunication system is provided. The method comprises receivingdetection configuration information from a second node and transmittinga detection signal to a neighboring node based on the detectionconfiguration information upon receiving detection request informationfrom the second node, wherein the detection signal is aperiodicallytransmitted, and the detection signal is transmitted on the basis ofbeam sweeping.

The first node may be connected with the second node via a backhaullink.

Data transmitted and received by the first node may be relayed by thesecond node.

The detection configuration information may be transmitted throughsystem information or radio resource control (RRC).

The detection request information may be transmitted through downlinkcontrol information (DCI) or RRC.

The detection request information may be cell-specific orgroup-specific.

The first node may transmit the detection signal using a synchronizationsignal block (SSB) transmitted to a user equipment (UE), and thedetection signal may be different from the SSB in at least one oftransmission timing and resource allocation.

The detection configuration information may comprise detection signalreception configuration information, the first node may receive adifferent detection signal transmitted by the neighboring node based onthe detection signal reception configuration information, and thedetection signal reception configuration information may inform at leastone of an identifier (ID) of the neighboring node, transmission timingof the different detection signal, and a reception beam direction list.

The first node may transmit detection feedback information about thedifferent detection signal to the second node when receiving thedifferent detection signal, and the detection feedback information maybe aperiodically transmitted.

The detection feedback information may comprise at least one of the IDof the neighboring node, a best beam direction index, and a referencesignal received power (RSRP) measurement result.

The first node may receive measurement configuration information fromthe second node, may transmit a first measurement signal to theneighboring node based on the measurement configuration information, andmay receive a second measurement signal from the neighboring node basedon the measurement configuration information, and the first measurementsignal and the second measurement signal may be periodicallytransmitted.

The first node may perform measurement based on the first measurementsignal and the second measurement signal and may select a particularnode having a best channel quality from among neighboring nodes based onthe measurement.

The first node may transmit measurement feedback information about themeasurement to the second node, and the measurement feedback informationmay be periodically transmitted.

The first node may transmit the detection signal after specifiedduration after receiving the detection request information, and thespecified duration may be configured independently for each node.

A transmission time for the detection signal may be preconfigured, andthe first node may transmit the detection signal at a nearesttransmission time after a specified offset from based on the detectionrequest information being received.

The specified offset may be configured in advance or may be determinedby the detection request information.

In another aspect, provided is a first node comprising a transceiverconfigured to transmit and receive a radio signal, and a processorconfigured to be operatively coupled with the transceiver, wherein theprocessor is configured to receive detection configuration informationfrom a second node and transmit a detection signal to a neighboring nodebased on the detection configuration information upon receivingdetection request information from the second node, the detection signalis aperiodically transmitted, and the detection signal is transmitted onthe basis of beam sweeping.

The first node may communicate with at least one of a mobile terminal, anetwork, and a self-driving vehicle other than the first node.

In another aspect, provided is a processor of a wireless communicationdevice in a wireless communication system, the processor controlling thewireless communication device to receive detection configurationinformation from a particular node, and to transmit a detection signalto a neighboring node based on the detection configuration informationupon receiving detection request information from the particular node,wherein the detection signal is aperiodically transmitted, and thedetection signal is transmitted based on beam sweeping.

The disclosure proposes a method in which an IAB node transmits a signalfor discovering and measuring another IAB node and performsdetection/discovery and measurement using the signal. Particularly, indetecting an IAB node, the IAB node aperiodically detects the target IABnode, making it possible to more efficiently perform detection than in adetection operation based on a conventional system.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a wireless communication system to which the presentdisclosure may be applied.

FIG. 2 is a diagram showing a wireless protocol architecture for a userplane.

FIG. 3 is a diagram showing a wireless protocol architecture for acontrol plane.

FIG. 4 illustrates a system structure of a next generation radio accessnetwork (NG-RAN) to which NR is applied.

FIG. 5 illustrates a functional division between an NG-RAN and a 5GC.

FIG. 6 illustrates an example of a frame structure that may be appliedin NR.

FIG. 7 illustrates CORESET.

FIG. 8 is a diagram illustrating a difference between a related artcontrol region and the CORESET in NR.

FIG. 9 illustrates an example of a frame structure for new radio accesstechnology.

FIG. 10 is an abstract schematic diagram illustrating hybrid beamformingfrom the viewpoint of TXRUs and physical antennas.

FIG. 11 illustrates the beam sweeping operation for a synchronizationsignal and system information in a downlink (DL) transmission procedure.

FIG. 12 schematically illustrates an example of a network having an IABlink.

FIG. 13 schematically illustrates an example of the configuration ofaccess and backhaul links.

FIG. 14 schematically illustrates an example in which a backhaul linkand an access link are configured when there are a DgNB and IAB relaynodes.

FIG. 15 schematically illustrates subframe offsets for a DgNB and RNs.

FIG. 16 schematically illustrates a process for discovery signaltransmission/reception and feedback.

FIG. 17 schematically illustrates an example in which discovery signaltransmission timing is applied according to the disclosure.

FIG. 18 schematically illustrates another example in which discoverysignal transmission timing is applied according to the disclosure.

FIG. 19 illustrates a process of discovering and measuring an IAB nodethrough a discovery signal according to the disclosure.

FIG. 20 schematically illustrates an example of a method for aperiodicdetection and periodic measurement of an IAB node according to thedisclosure.

FIG. 21 is a flowchart illustrating a detection method performed by afirst node according to an embodiment of the disclosure.

FIG. 22 schematically shows an example to which the disclosure isapplied.

FIG. 23 is a flowchart illustrating a method in which a node perform anaperiodic detection operation and a periodic measurement operationaccording to an embodiment of the disclosure.

FIG. 24 is a flowchart illustrating a method in which a node perform aperiodic detection operation and a periodic measurement operationaccording to an embodiment of the disclosure.

FIG. 25 illustrates a wireless communication device according to anembodiment of the disclosure.

FIG. 26 is a block diagram showing components of a transmitting device1810 and a receiving device 1820 for implementing the presentdisclosure.

FIG. 27 illustrates an example of a signal processing module structurein the transmitting device 1810.

FIG. 28 illustrates another example of the signal processing modulestructure in the transmitting device 1810.

FIG. 29 illustrates an example of a wireless communication deviceaccording to an implementation example of the present disclosure.

FIG. 30 shows examples of 5G usage scenarios to which the technicalfeatures of the present disclosure can be applied.

FIG. 31 shows an example of an AI device 31100 to which the technicalfeatures of the present disclosure can be applied.

FIG. 32 illustrates an AI server 32200 according to an embodiment of thedisclosure.

FIG. 33 shows an example of an AI system 331 to which the technicalfeatures of the present disclosure can be applied.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

FIG. 1 shows a wireless communication system to which the presentdisclosure may be applied. The wireless communication system may bereferred to as an Evolved-UMTS Terrestrial Radio Access Network(E-UTRAN) or a Long Term Evolution (LTE)/LTE-A system.

The E-UTRAN includes at least one base station (BS) 20 which provides acontrol plane and a user plane to a user equipment (UE) 10. The UE 10may be fixed or mobile, and may be referred to as another terminology,such as a mobile station (MS), a user terminal (UT), a subscriberstation (SS), a mobile terminal (MT), a wireless device, etc. The BS 20is generally a fixed station that communicates with the UE 10 and may bereferred to as another terminology, such as an evolved node-B (eNB), abase transceiver system (BTS), an access point, etc.

The BSs 20 are interconnected by means of an X2 interface. The BSs 20are also connected by means of an S1 interface to an evolved packet core(EPC) 30, more specifically, to a mobility management entity (MME)through S1-MME and to a serving gateway (S-GW) through S1-U.

The EPC 30 includes an MME, an S-GW, and a packet data network-gateway(P-GW). The MME has access information of the UE or capabilityinformation of the UE, and such information is generally used formobility management of the UE. The S-GW is a gateway having an E-UTRANas an end point. The P-GW is a gateway having a PDN as an end point.

Layers of a radio interface protocol between the UE and the network canbe classified into a first layer (L1), a second layer (L2), and a thirdlayer (L3) based on the lower three layers of the open systeminterconnection (OSI) model that is well-known in the communicationsystem. Among them, a physical (PHY) layer belonging to the first layerprovides an information transfer service by using a physical channel,and a radio resource control (RRC) layer belonging to the third layerserves to control a radio resource between the UE and the network. Forthis, the RRC layer exchanges an RRC message between the UE and the BS.

FIG. 2 is a diagram showing a wireless protocol architecture for a userplane. FIG. 3 is a diagram showing a wireless protocol architecture fora control plane. The user plane is a protocol stack for user datatransmission. The control plane is a protocol stack for control signaltransmission.

Referring to FIGS. 2 and 3, a PHY layer provides an upper layer with aninformation transfer service through a physical channel. The PHY layeris connected to a medium access control (MAC) layer which is an upperlayer of the PHY layer through a transport channel. Data is transferredbetween the MAC layer and the PHY layer through the transport channel.The transport channel is classified according to how and with whatcharacteristics data is transferred through a radio interface.

Data is moved between different PHY layers, that is, the PHY layers of atransmitter and a receiver, through a physical channel. The physicalchannel may be modulated according to an Orthogonal Frequency DivisionMultiplexing (OFDM) scheme, and use the time and frequency as radioresources.

The functions of the MAC layer include mapping between a logical channeland a transport channel and multiplexing and demultiplexing to atransport block that is provided through a physical channel on thetransport channel of a MAC Service Data Unit (SDU) that belongs to alogical channel. The MAC layer provides service to a Radio Link Control(RLC) layer through the logical channel.

The functions of the RLC layer include the concatenation, segmentation,and reassembly of an RLC SDU. In order to guarantee various types ofQuality of Service (QoS) required by a Radio Bearer (RB), the RLC layerprovides three types of operation mode: Transparent Mode (TM),Unacknowledged Mode (UM), and Acknowledged Mode (AM). AM RLC provideserror correction through an Automatic Repeat Request (ARQ).

The RRC layer is defined only on the control plane. The RRC layer isrelated to the configuration, reconfiguration, and release of radiobearers, and is responsible for control of logical channels, transportchannels, and PHY channels. An RB means a logical route that is providedby the first layer (PHY layer) and the second layers (MAC layer, the RLClayer, and the PDCP layer) in order to transfer data between UE and anetwork.

The function of a Packet Data Convergence Protocol (PDCP) layer on theuser plane includes the transfer of user data and header compression andciphering. The function of the PDCP layer on the user plane furtherincludes the transfer and encryption/integrity protection of controlplane data.

What an RB is configured means a process of defining the characteristicsof a wireless protocol layer and channels in order to provide specificservice and configuring each detailed parameter and operating method. AnRB can be divided into two types of a Signaling RB (SRB) and a Data RB(DRB). The SRB is used as a passage through which an RRC message istransmitted on the control plane, and the DRB is used as a passagethrough which user data is transmitted on the user plane.

If RRC connection is established between the RRC layer of UE and the RRClayer of an E-UTRAN, the UE is in the RRC connected state. If not, theUE is in the RRC idle state.

A downlink transport channel through which data is transmitted from anetwork to UE includes a broadcast channel (BCH) through which systeminformation is transmitted and a downlink shared channel (SCH) throughwhich user traffic or control messages are transmitted. Traffic or acontrol message for downlink multicast or broadcast service may betransmitted through the downlink SCH, or may be transmitted through anadditional downlink multicast channel (MCH). Meanwhile, an uplinktransport channel through which data is transmitted from UE to a networkincludes a random access channel (RACH) through which an initial controlmessage is transmitted and an uplink shared channel (SCH) through whichuser traffic or control messages are transmitted.

Logical channels that are placed over the transport channel and that aremapped to the transport channel include a broadcast control channel(BCCH), a paging control channel (PCCH), a common control channel(CCCH), a multicast control channel (MCCH), and a multicast trafficchannel (MTCH).

The physical channel includes several OFDM symbols in the time domainand several subcarriers in the frequency domain. One subframe includes aplurality of OFDM symbols in the time domain. An RB is a resourcesallocation unit, and includes a plurality of OFDM symbols and aplurality of subcarriers. Furthermore, each subframe may use specificsubcarriers of specific OFDM symbols (e.g., the first OFDM symbol) ofthe corresponding subframe for a physical downlink control channel(PDCCH), that is, an L1/L2 control channel. A Transmission Time Interval(TTI) is a unit time for subframe transmission.

Hereinafter, a new radio access technology (new RAT, NR) will bedescribed.

As more and more communication devices require more communicationcapacity, there is a need for improved mobile broadband communicationover existing radio access technology. Also, massive machine typecommunications (MTC), which provides various services by connecting manydevices and objects, is one of the major issues to be considered in thenext generation communication. In addition, communication system designconsidering reliability/latency sensitive service/UE is being discussed.The introduction of next generation radio access technology consideringenhanced mobile broadband communication (eMBB), massive MTC (mMTC),ultra-reliable and low latency communication (URLLC) is discussed. Thisnew technology may be called new radio access technology (new RAT or NR)in the present disclosure for convenience.

FIG. 4 illustrates a system structure of a next generation radio accessnetwork (NG-RAN) to which NR is applied.

Referring to FIG. 4, the NG-RAN may include a gNB and/or an eNB thatprovides user plane and control plane protocol termination to aterminal. FIG. 4 illustrates the case of including only gNBs. The gNBand the eNB are connected by an Xn interface. The gNB and the eNB areconnected to a 5G core network (5GC) via an NG interface. Morespecifically, the gNB and the eNB are connected to an access andmobility management function (AMF) via an NG-C interface and connectedto a user plane function (UPF) via an NG-U interface.

FIG. 5 illustrates a functional division between an NG-RAN and a 5GC.

The gNB may provide functions such as an inter-cell radio resourcemanagement (Inter Cell RRM), radio bearer management (RB control),connection mobility control, radio admission control, measurementconfiguration & provision, dynamic resource allocation, and the like.The AMF may provide functions such as NAS security, idle state mobilityhandling, and so on. The UPF may provide functions such as mobilityanchoring, PDU processing, and the like. The SMF may provide functionssuch as UE IP address assignment, PDU session control, and so on.

FIG. 6 illustrates an example of a frame structure that may be appliedin NR.

Referring to FIG. 6, a frame may be composed of 10 milliseconds (ms) andinclude 10 subframes each composed of 1 ms.

One or a plurality of slots may be included in a subframe according tosubcarrier spacings.

The following table 1 illustrates a subcarrier spacing configuration n

TABLE 1 μ Δf = 2^(μ) · 15 [kHz] Cyclic prefix 0 15 Normal 1 30 Normal 260 Normal Extended 3 120 Normal 4 240 Normal

The following table 2 illustrates the number of slots in a frame(N^(frame,μ)slot), the number of slots in a subframe (N^(frame,μ)slot),(N the number of symbols in a slot (N^(frame,μ)slot), and the like,according to subcarrier spacing configurations u.

TABLE 2 μ N_(symb) ^(slot) N_(slot) ^(frame, μ) N_(slot) ^(subframe, μ)0 14 10 1 1 14 20 2 2 14 40 4 3 14 80 8 4 14 160 16

In FIG. 6, μ=0, 1, 2 is illustrated.

A physical downlink control channel (PDCCH) may include one or morecontrol channel elements (CCEs) as illustrated in the following table 3.

TABLE 3 Aggregation level Number of CCEs 1 1 2 2 4 4 8 8 16 16

That is, the PDCCH may be transmitted through a resource including 1, 2,4, 8, or 16 CCEs. Here, the CCE includes six resource element groups(REGs), and one REG includes one resource block in a frequency domainand one orthogonal frequency division multiplexing (OFDM) symbol in atime domain.

Meanwhile, in a future wireless communication system, a new unit calleda control resource set (CORESET) may be introduced. The terminal mayreceive the PDCCH in the CORESET.

FIG. 7 illustrates CORESET.

Referring to FIG. 7, the CORESET includes N^(CORESET) number of resourceblocks in the frequency domain, and N^(CORESET) _(symb)∈{11, 2, 3}number of symbols in the time domain. N^(CORESET) _(RB) and N^(CORESET)_(symb) may be provided by a base station via higher layer signaling. Asillustrated in FIG. 7, a plurality of CCEs (or REGs) may be included inthe CORESET.

The UE may attempt to detect a PDCCH in units of 1, 2, 4, 8, or 16 CCEsin the CORESET. One or a plurality of CCEs in which PDCCH detection maybe attempted may be referred to as PDCCH candidates.

A plurality of CORESETs may be configured for the terminal.

FIG. 8 is a diagram illustrating a difference between a related artcontrol region and the CORESET in NR.

Referring to FIG. 8, a control region 800 in the related art wirelesscommunication system (e.g., LTE/LTE-A) is configured over the entiresystem band used by a base station (BS). All the terminals, excludingsome (e.g., eMTC/NB-IoT terminal) supporting only a narrow band, must beable to receive wireless signals of the entire system band of the BS inorder to properly receive/decode control information transmitted by theBS.

On the other hand, in NR, CORESET described above was introduced.CORESETs 801, 802, and 803 are radio resources for control informationto be received by the terminal and may use only a portion, rather thanthe entirety of the system bandwidth. The BS may allocate the CORESET toeach UE and may transmit control information through the allocatedCORESET. For example, in FIG. 8, a first CORESET 801 may be allocated toUE 1, a second CORESET 802 may be allocated to UE 2, and a third CORESET803 may be allocated to UE 3. In the NR, the terminal may receivecontrol information from the BS, without necessarily receiving theentire system band.

The CORESET may include a UE-specific CORESET for transmittingUE-specific control information and a common CORESET for transmittingcontrol information common to all UEs.

Meanwhile, NR may require high reliability according to applications. Insuch a situation, a target block error rate (BLER) for downlink controlinformation (DCI) transmitted through a downlink control channel (e.g.,physical downlink control channel (PDCCH)) may remarkably decreasecompared to those of conventional technologies. As an example of amethod for satisfying requirement that requires high reliability,content included in DCI can be reduced and/or the amount of resourcesused for DCI transmission can be increased. Here, resources can includeat least one of resources in the time domain, resources in the frequencydomain, resources in the code domain and resources in the spatialdomain.

In NR, the following technologies/features can be applied.

<Self-Contained Subframe Structure>

FIG. 9 illustrates an example of a frame structure for new radio accesstechnology.

In NR, a structure in which a control channel and a data channel aretime-division-multiplexed within one TTI, as shown in FIG. 9, can beconsidered as a frame structure in order to minimize latency.

In FIG. 9, a shaded region represents a downlink control region and ablack region represents an uplink control region. The remaining regionmay be used for downlink (DL) data transmission or uplink (UL) datatransmission. This structure is characterized in that DL transmissionand UL transmission are sequentially performed within one subframe andthus DL data can be transmitted and UL ACK/NACK can be received withinthe subframe. Consequently, a time required from occurrence of a datatransmission error to data retransmission is reduced, thereby minimizinglatency in final data transmission.

In this data and control TDMed subframe structure, a time gap for a basestation and a terminal to switch from a transmission mode to a receptionmode or from the reception mode to the transmission mode may berequired. To this end, some OFDM symbols at a time when DL switches toUL may be set to a guard period (GP) in the self-contained subframestructure.

<Analog Beamforming #1>

Wavelengths are shortened in millimeter wave (mmW) and thus a largenumber of antenna elements can be installed in the same area. That is,the wavelength is 1 cm at 30 GHz and thus a total of 100 antennaelements can be installed in the form of a 2-dimensional array at aninterval of 0.5 lambda (wavelength) in a panel of 5×5 cm. Accordingly,it is possible to increase a beamforming (BF) gain using a large numberof antenna elements to increase coverage or improve throughput in mmW.

In this case, if a transceiver unit (TXRU) is provided to adjusttransmission power and phase per antenna element, independentbeamforming per frequency resource can be performed. However,installation of TXRUs for all of about 100 antenna elements decreaseseffectiveness in terms of cost. Accordingly, a method of mapping a largenumber of antenna elements to one TXRU and controlling a beam directionusing an analog phase shifter is considered. Such analog beamforming canform only one beam direction in all bands and thus cannot providefrequency selective beamforming.

Hybrid beamforming (BF) having a number B of TXRUs which is smaller thanQ antenna elements can be considered as an intermediate form of digitalBF and analog BF. In this case, the number of directions of beams whichcan be simultaneously transmitted are limited to B although it dependson a method of connecting the B TXRUs and the Q antenna elements.

<Analog Beamforming #2>

When a plurality of antennas is used in NR, hybrid beamforming which isa combination of digital beamforming and analog beamforming is emerging.Here, in analog beamforming (or RF beamforming) an RF end performsprecoding (or combining) and thus it is possible to achieve theperformance similar to digital beamforming while reducing the number ofRF chains and the number of D/A (or A/D) converters. For convenience,the hybrid beamforming structure may be represented by N TXRUs and Mphysical antennas. Then, the digital beamforming for the L data layersto be transmitted at the transmitting end may be represented by an N byL matrix, and the converted N digital signals are converted into analogsignals via TXRUs, and analog beamforming represented by an M by Nmatrix is applied.

FIG. 10 is an abstract schematic diagram illustrating hybrid beamformingfrom the viewpoint of TXRUs and physical antennas.

In FIG. 10, the number of digital beams is L and the number of analogbeams is N. Further, in the NR system, by designing the base station tochange the analog beamforming in units of symbols, it is considered tosupport more efficient beamforming for a terminal located in a specificarea. Furthermore, when defining N TXRUs and M RF antennas as oneantenna panel in FIG. 7, it is considered to introduce a plurality ofantenna panels to which independent hybrid beamforming is applicable inthe NR system.

When a base station uses a plurality of analog beams as described above,analog beams suitable to receive signals may be different for terminalsand thus a beam sweeping operation of sweeping a plurality of analogbeams to be applied by a base station per symbol in a specific subframe(SF) for at least a synchronization signal, system information andpaging such that all terminals can have reception opportunities isconsidered.

FIG. 11 illustrates the beam sweeping operation for a synchronizationsignal and system information in a downlink (DL) transmission procedure.

In FIG. 11, physical resources (or a physical channel) in which systeminformation of the NR system is transmitted in a broadcasting manner isreferred to as a physical broadcast channel (xPBCH). Here, analog beamsbelonging to different antenna panels can be simultaneously transmittedwithin one symbol, and a method of introducing a beam reference signal(BRS) which is a reference signal (RS) to which a single analog beam(corresponding to a specific antenna panel) is applied in order tomeasure a channel per analog beam, as illustrated in FIG. 8, is underdiscussion. The BRS can be defined for a plurality of antenna ports, andeach antenna port of the BRS can correspond to a single analog beam.Here, all analog beams in an analog beam group are applied to thesynchronization signal or xPBCH and then the synchronization signal orxPBCH is transmitted such that an arbitrary terminal can successivelyreceive the synchronization signal or xPBCH.

Hereinafter, an integrated access and backhual link (IAB) link will bedescribed.

One of the potential technologies targeted to enable future cellularnetwork deployment scenarios and applications is the support forwireless backhaul and relay links enabling flexible and very densedeployment of NR cells without the need for densifying the transportnetwork proportionately.

Due to the expected larger bandwidth available for NR compared to LTE(e.g. mmWave spectrum) along with the native deployment of massive MIMOor multi-beam systems in NR creates an opportunity to develop and deployintegrated access and backhaul links. This may allow easier deploymentof a dense network of self-backhauled NR cells in a more integratedmanner by building upon many of the control and data channels/proceduresdefined for providing access to UEs.

FIG. 12 schematically illustrates an example of a network having an IABlink.

Referring to FIG. 12, relay nodes (rTRP) may multiplex access andbackhaul links in a time, frequency, or space domain (i.e., a beam-basedoperation).

The operation of the different links may be on the same or differentfrequencies (also termed ‘in-band’ and ‘out-band’ relays). Whileefficient support of out-band relays is important for some NR deploymentscenarios, it is critically important to understand the requirements ofin-band operation which imply tighter interworking with the access linksoperating on the same frequency to accommodate duplex constraints andavoid/mitigate interference.

In addition, operating NR systems in mmWave spectrum presents someunique challenges including experiencing severe short-term blocking thatmay not be readily mitigated by present RRC-based handover mechanismsdue to the larger time-scales required for completion of the procedurescompared to short-term blocking. Overcoming short-term blocking inmmWave systems may require fast RAN-based mechanisms for switchingbetween rTRPs, which do not necessarily require involvement of the corenetwork. The above described need to mitigate short-term blocking for NRoperation in mmWave spectrum along with the desire for easier deploymentof self-backhauled NR cells creates a need for the development of anintegrated framework that allows fast switching of access and backhaullinks. Over-the-air (OTA) coordination between rTRPs can also beconsidered to mitigate interference and support end-to-end routeselection and optimization.

The following requirements and aspects should be addressed by theintegrated access and wireless backhaul (IAB) for NR:

-   -   Efficient and flexible operation for both inband and outband        relaying in indoor and outdoor scenarios    -   Multi-hop and redundant connectivity    -   End-to-end route selection and optimization    -   Support of backhaul links with high spectral efficiency    -   Support of legacy NR UEs

Legacy New RAT is designed to support half-duplex devices. We alsothinks half-duplex in IAB scenario deserves to be supported andtargeted. In addition, IAB devices with full duplex also can be studied.

In IAB scenario, if each relay node (RN) doesn't have schedulingability, a Donor gNB (DgNB) should schedules the entire links among theDgNB, associated RNs, and UEs. In other words, a DgNB should makescheduling decisions for all links by gathers traffic information fromthe entire associated RNs, then inform the scheduling information toeach RN.

FIG. 13 schematically illustrates an example of the configuration ofaccess and backhaul links.

Referring to FIG. 13, the DgNB not only receive scheduling request ofUE1, but also receive scheduling request of UE2 and UE3. Then, it makesscheduling decision of two backhaul links and three access links, andinform the scheduling results. Therefore, this centralized schedulingwould involve scheduling delay and cause latency issue.

In the other hand, distributed scheduling can be made if each RN hasscheduling ability. Then, immediate scheduling can be made for uplinkscheduling request of UE, and backhaul/access links can be utilized moreflexibly by reflecting the surrounding traffic situation.

Hereinafter, the disclosure will be described.

The disclosure proposes a method in which an IAB node transmits signalsfor discovery and measurement of another IAB node and performs discoveryand measurement using the signals in a new RAT environment. Here, thesignals used for the discovery and measurement may be referred to as adiscovery signal and a measurement signal, respectively.

In the disclosure, for the convenience of description, the proposedmethod will be described on the basis of a new RAT (NR) system. However,the proposed method may also be applicable to other systems, such as3GPP LTE/LTE-A systems, in addition to the new RAT system.

Further, the disclosure is described in view of an in-band environmentbut may also be applied to an out-band environment.

In addition, the disclosure is described in view of an environment inwhich a donor gNB (DgNB), a relay node (RN), and a UEperform ahalf-duplex operation but may also be applied to an environment in whicha DgNB, an RN, and/or a UE perform a full-duplex operation.

In the disclosure, for the convenience of description, when RN 1 and RN2 exist, and RN 1 is connected to RN 2 via a backhaul link and relaysdata transmitted to/received from RN 2, RN 1 is referred to as a parentnode of RN 2, and RN 2 is referred to as a child node of RN 1.

As used herein, a discovery signal is a signal transmitted by an IABnode, which is a signal transmitted to enable other IAB nodes or UEs todiscover the IAB node.

This discovery signal may be in the form of a synchronization signalblock (SSB) according to an NR specification, in the form of a channelstate information-reference signal (CSI-RS), or in the form of a signaladopted according to different existing NR. Alternatively, the discoverysignal may be a newly designed signal. In NR, in the time domain, asynchronization signal block (SSB, a synchronization signal and aphysical broadcast channel (PBCH)) may include four OFDM symbolsnumbered from 0 to 3 in ascending order in the synchronization signalblock, and a PBCH associated with a primary synchronization signal(PSS), a secondary synchronization signal (SSS), and a demodulationreference signal (DMRS) may be mapped to the symbols. Thesynchronization signal block may also be referred to as an SS/PBCHblock.

The disclosure mainly illustrates an IAB node discovering other IABnodes but may also be applied to a case where a UE discovers IAB nodes.

FIG. 14 schematically illustrates an example in which a backhaul linkand an access link are configured when there are a DgNB and IAB relaynodes.

According to FIG. 14, RN(b) and RN(e) are connected to DgNB(a) viabackhaul links, RN(c) is connected to RN(b) via a backhaul link, andRN(d) is connected to RN(c) via a backhaul link.

In the disclosure, a backhaul link between node (x) and node (y) isreferred to as BH_xy. An access link between node (x) and a UE isreferred to as AC_x. Referring to FIG. 14, an access link betweenDgNB(a) and UE1 may be referred to as AC_a, an access link between RN(c)and UE3 may be referred to as AC_c. Further, in FIG. 14, the backhaullink between RN(b) and RN(c) may be referred to as BH_bc.

Hereinafter, a method for transmitting and receiving a discovery signalaccording to the type of a used signal will be described.

In the disclosure, a discovery signal may mean a signal for detectingand/or measuring another node. When a discovery signal is usedseparately as a signal for detection or a signal for measurement, thefollowing disclosure may be applied only to the signal for detection,only to the signal for measurement, or both of the signals.

First, discovery signal transmission based on a synchronization signalblock (SSB) will be described.

In NR, in the time domain, a synchronization signal block (SSB, asynchronization signal and a physical broadcast channel (PBCH)) mayinclude four OFDM symbols numbered from 0 to 3 in ascending order in thesynchronization signal block, and a PBCH associated with a primarysynchronization signal (PSS), a secondary synchronization signal (SSS),and a demodulation reference signal (DMRS) may be mapped to the symbols.The synchronization signal block may also be referred to as an SS/PBCHblock.

In order for an IAB node to discover other IAB nodes, a conventionallytransmitted SSB may be used as a discovery signal. That is, instead ofdefining and transmitting a separate additional discovery signal, an RNmay discover another node using an existing SSB.

However, as described below, an SSB according to the disclosure may bethe same as an existing SSB that a base station transmits to a UE butmay be different from the foregoing SSB according to NR in terms ofconfiguration, a resource allocation method, and the like. That is, theSSB according to the disclosure may be an SSB transmitted through abackhaul link between base stations, which may be referred to as abackhaul-SSB. Here, a backhaul-SSB may be the same as or different fromthe SSB that a base station transmits to a UE.

When an RN performs a half-duplex operation, the RN cannot transmit anSBS and receive an SBS at the same time. Therefore, for the RN toreceive an SSB transmitted by a different node, nodes that need todiscover each other needs to transmit SSBs at different positions(orthogonal positions). However, a conventional SSB transmission methodmay make it difficult for the nodes to transmit SSBs using orthogonalresources.

Therefore, in order to increase flexibility of SSB transmissionresources, the disclosure proposes applying an offset to a frameboundary (or system frame boundary) between nodes.

In this case, SSB transmission times for the nodes may be different, andthus the nodes are more likely to transmit SSBs using orthogonalresources.

To this end, a frame boundary offset (or system frame boundary offset)may be determined as follows.

[Method A]

A frame boundary offset (or system frame boundary offset) for an RN mayvary depending on the number of hops from a DgNB to the RN. Defining thenumber of hops from the DgNB to RN(x) is C_x, the frame boundary (orsystem frame boundary) of RN(x) has an offset of α*C_xsymbols/mini-slots/slots/subframes/frames from the frame boundary (orsystem frame boundary) of the DgNB. It is offset by. Particularly, whenthe maximum offset value (e.g., C_max) is limited, the frame boundary(or system frame boundary) of RN(x) may have an offset of α*C_x modC_max symbols/mini-slots/slots/subframes/frames.

FIG. 15 schematically illustrates subframe offsets for a DgNB and RNs.

In FIG. 15, it is assumed that an IAB system includes DgNB(a), RN(b),RN(c), and RN(d). Here, when C_b, C_c, and C_d are 1, 2, and 3,respectively, the frame boundaries of RN(b), RN(c), and RN(d) mayrespectively have offsets of one, two, and three subframes from theframe boundary of DgNB(a).

In particular, considering that an SSB is transmitted within a window of5 milliseconds (ms), an offset may be a multiple of 5 ms. For example, amay be five subframes/ms or a multiple of five subframes/ms. Thus, theframe boundary (or system frame boundary) of RN(x) may have an offset of5*C_x subframes from the frame boundary (or system frame boundary) ofthe DgNB. Further, considering that a default period for SSBtransmission is 20 ms, C_max may be configured to be 20 subframes/ms.Alternatively, α and/or C_max may be configured via system information(SI), RRC, or the like.

[Method B]

A frame boundary offset (or system frame boundary offset) for an RN mayvary depending on whether the number of hops from a DgNB to the RN is anodd number or an even number. For example, when the number of hops fromthe DgNB to the RN is an odd number, the RN may have a frame boundaryoffset (or system frame boundary offset) of a slots/subframes; when thenumber of hops from the DgNB to the RN is an even number, the RN mayhave a frame boundary offset (or system frame boundary offset) of 0slots/subframes. In this case, when there is a multi-path to each RN,the RN may have a different hop count for each path. In this case, therelay node may perform transmission according to the number of hops in aprimary path, the number of hops in the shortest path, the number ofhops in the longest path, or the number of hops in a path determined bythe DgNB. Here, the primary path may be a path to which the RN isconnected, a path to which the RN has established a connection earlier,a path through which the RN monitors a control channel, and/or a pathconfigured as a primary path by a parent node.

In particular, considering that an SSB is transmitted within a window of5 ms, a may be five subframes/ms or a multiple of five subframes/ms. Forexample, when the number of hops from the DgNB to the RN is an oddnumber, the RN may have a frame boundary offset (or system frameboundary offset) of 5 slots/subframes; when the number of hops from theDgNB to the RN is an even number, the RN may have a frame boundaryoffset (or system frame boundary offset) of 0 slots/subframes.Alternatively, a may be configured via system information (SI), RRC, orthe like.

[Method C]

Assuming that there may be K boundary frame offsets (or slot offsets) intotal, RNs having the same value obtained by the number of hops from aDgNB to an RN H % K (or mod (H, K)) may use the same offset, and RNshaving different values obtained by the number of hops from the DgNB tothe RN H % K may use different offsets. For example, when K=3, RNsrespectively having one hop and four hops have a different offset fromthat for RNs respectively having two hops and five hops. When there is amulti-path to each RN, the RN may have a different hop count for eachpath. In this case, the relay node may perform transmission according tothe number of hops in a primary path, the number of hops in the shortestpath, the number of hops in the longest path, or the number of hops in apath determined by the DgNB.

When [Method B] or [Method C] is used, it is possible to limit anSS/PBCH block measurement time configuration (SMTC) to twoslots/subframes or K slots/subframes.

Next, discovery signal transmission based on a CSI-RS will be described.

This method may be for detecting and/or measuring an IAB node on thebasis of a CSI-RS. Specific methods using a CSI-RS are illustratedbelow.

-   -   Method in which a CSI-RS is configured only for measurement        (assuming that a CSI-RS is not used as a discovery signal)    -   Method in which a CSI-RS is assumed to be used only as a        discovery signal (assuming that a CSI-RS is not used for        measurement)    -   Method in which a CSI-RS is available as a measurement and        discovery signal.

Here, a CSI-RS configuration method may vary according to each method,and the following specific methods may be taken into consideration.

-   -   A method of configuring a dedicated CSI-RS for each pair may be        taken into consideration. Each DgNB or RN may configure a        dedicated CSI-RS for each of RNs that need to measure the DgNB        or RN. This method may be particularly useful for setting        different pairs when Tx-Rx beam pairs are different for each        pair. When a CSI-RS is configured with respect to a particular        beam pair(s) for each pair, if a beam exceeding a threshold is        not discovered with respect to a neighboring node on the basis        of a CSI-RS, each RN may fall back to measurement using an SSB.        This method may be performed only when a fallback is requested.        Alternatively, each DgNB/RN may configure a measurement (CSI-RS)        relating to a neighboring node for a child node(s) thereof. That        is, the DgNB or RN currently performs, for a child RN, an        operation similar to an operation of performing radio resource        management (RRM) measurement configuration of a CSI-RS for a UE.    -   In order to find the best beam pair for each RN, a CSI-RS may        also be transmitted by beam sweeping. In this case, a period and        an offset used for each DgNB/RN to perform beam sweeping of a        CSI-RS, the number of beam sweeping times in each sweeping        interval m and the number of times each beam is repeated (e.g.,        the number of Tx beam sweeping times*the number of Rx beam        sweeping times) may be indicated, thus enabling neighboring        nodes to perform measurement according to a transmission period.        When this transmission method is used, CSI-RS transmission        timing may have a different offset for transmitting a CSI-RS per        hop or node using a method similar to a method of shifting a        slot/frame/subframe boundary described above in SSB-based        discovery signal transmission.

Next, discovery signal transmission based on a CSI-RS will be described.

A method for detecting and/or measuring an IAB node on the basis of aCSI-RS may be taken into consideration. In this case, the followingmethods may be taken into consideration.

-   -   Method in which a CSI-RS is configured only for measurement        (assuming that a CSI-RS is not used as a discovery signal)    -   Method in which a CSI-RS is assumed to be used only as a        discovery signal (assuming that a CSI-RS is not used for        measurement)    -   Method in which a CSI-RS is available as a measurement and        discovery signal.    -   Method of configuring a dedicated CSI-RS for each pair

That is, each DgNB or RN may configure a dedicated CSI-RS for each ofRNs that need to measure the DgNB or RN. This method may be particularlyuseful for setting different pairs when Tx-Rx beam pairs are differentfor each pair. When a CSI-RS is configured with respect to a particularbeam pair(s) for each pair, if a beam exceeding a threshold is notdiscovered with respect to a neighboring node on the basis of a CSI-RS,each RN may fall back to measurement using an SSB. This method may beperformed only when a fallback is requested. Alternatively, each DgNB/RNmay configure a measurement (CSI-RS) relating to a neighboring node fora child node(s) thereof. That is, the DgNB or RN currently performs, fora child RN, an operation similar to an operation of performing RRMmeasurement configuration of a CSI-RS for a UE.

-   -   Method of transmitting a CSI-RS by beam sweeping in order to        find the best beam pair for each RN

In this case, a period and an offset used for each DgNB/RN to performbeam sweeping of a CSI-RS, the number of beam sweeping times in eachsweeping interval m and the number of times each beam is repeated (e.g.,the number of Tx beam sweeping times*the number of Rx beam sweepingtimes) may be indicated, thus enabling neighboring nodes to performmeasurement according to a transmission period. When this transmissionmethod is used, CSI-RS transmission timing may have a different offsetfor transmitting a CSI-RS per hop or node using a method similar to amethod of shifting a slot/frame/subframe boundary described above inSSB-based discovery signal transmission.

Considering an environment with no or low mobility of a node, a casewhere a new node occurs among cases where nodes need to discover aneighboring node may be taken into consideration. This case rarelyoccurs, in which it may be very inefficient to periodically transmit andreceive a discovery signal in order to discover a node.

Therefore, it is proposed below that nodes transmit a discovery signalto discover each other when a new RN is connected. That is, it isproposed that nodes aperiodicly transmit a discovery signal if needed.

First, a discovery procedure proposed in the disclosure will bedescribed.

When a new node performs initial access to a particular node toestablish a connection, nodes may transmit a discovery signal and maydiscover neighboring nodes through the following process.

a) Discovery Signal Transmission Configuration

A node may receive a configuration about transmission of a discoverysignal thereof from a parent node. This configuration may be determinedand provided for the child node by the parent node. Alternatively, aDgNB may determine the configuration and may report the configuration toeach associated node. In this case, the parent node may forward thisconfiguration, received from the DgNB, to the child node. Thisconfiguration may be transmitted via system information (e.g., remainingminimum system information (RMSI) or other system information (OSI)),message 4 (Msg 4), or RRC. Here, message 4 may be a contentionresolution message transmitted from a base station to a UE in a randomaccess procedure.

The configuration may include some or all of the following information.Further, through the configuration, the node may receive informationabout a period, an offset, and duration and may determine discoverysignal timing thereof using the received information, a hop countthereof, and path information.

-   -   Discovery signal transmission timing information: This        information may follow a discovery signal transmission-related        configuration specified in a discovery signal configuration for        transmission and reception of a discovery signal for detection        and measurement described below.

b) Discovery Signal Detection/Measurement Configuration

The node receives a configuration about a discovery signal transmittedby neighboring nodes from the parent node. This configuration may bedetermined and provided for the child node by the parent node.Alternatively, the DgNB may determine the configuration and may reportthe configuration to each associated node. In this case, the parent nodemay forward this configuration, received from the DgNB, to the childnode. This configuration may be transmitted via system information(e.g., RMSI or OSI), message 4 (Msg 4), or RRC.

When there is a plurality of nodes transmitting a discovery signal,information about each node may be transmitted. The configuration mayinclude some or all of the following information. Further, through theconfiguration, the node may receive information about a period, anoffset, and duration and may perform detection at the time when the nodedoes not perform transmission on the basis of the received information.In this case, each RN may not accurately identify which node transmits adiscovery signal at which time.

-   -   Node identification (ID, i.e., cell ID or virtual cell ID)    -   Discovery signal detection timing information

This information may follow a discovery signal transmission-relatedconfiguration specified in a discovery signal configuration fortransmission and reception of a discovery signal for detection andmeasurement described below.

c) Discovery Signal Transmission and Detection Request

The node may receive, from the parent node, a request to transmit adiscovery signal and to detect a discovery signal transmitted byneighboring nodes. This request may be determined and configured for thechild node by the parent node. Alternatively, the DgNB may determine therequest and may report the configuration to each associated node. Inthis case, the parent node may forward this request, received from theDgNB, to the child node. This request may be transmitted via message 4,RRC, and/or a PDCCH (DCI). Since transmission and reception of adiscovery signal needs to be performed by a plurality of nodes together,the request may be transmitted through cell-specific or group-specificRRC or PDCCH (DCI).

This information may follow a discovery signal transmission-relatedconfiguration specified in a discovery signal configuration fortransmission and reception of a discovery signal for detection andmeasurement described below.

d) Discovery Signal Transmission and Detection

A UE receiving a request to transmit and detect a discovery signal maytransmits a discovery signal thereof using information set according toa discovery signal transmission configuration and may detect a discoverysignal transmitted by a neighboring node using information set accordingto the discovery signal detection configuration.

e) Discovery Signal Detection Feedback

Upon detecting a discovery signal transmitted from neighboring nodes,the node may transmit feedback thereon to the parent node and/or theDgNB. This feedback may include some or all of the followinginformation.

-   -   Node ID (i.e., cell ID or virtual cell ID)    -   Best beam direction index    -   Result of measuring reference signal received power (RSRP) (or        reference signal received quality (RSRQ))

This information may follow a discovery signal transmission-relatedconfiguration specified in a discovery signal configuration fortransmission and reception of a discovery signal for detection andmeasurement described below.

FIG. 16 schematically illustrates a process for discovery signaltransmission/reception and feedback.

Referring to FIG. 16, a parent node transmits a discovery signaltransmission configuration and a discovery signal detectionconfiguration to a child node (S1610 and S1620). Although FIG. 16 showsthat the configurations are transmitted in two separate steps, theconfigurations may be transmitted at the same time. Alternatively, thediscovery signal transmission configuration and/or the discovery signaldetection configuration may not be transmitted in advance but may betransmitted together with a discovery signal transmission and detectionrequest. Further, even though the discovery signal transmissionconfiguration and/or the discovery signal detection configuration aretransmitted, the discovery signal transmission configuration and/or thediscovery signal detection configuration may be additionally transmittedtogether with a discovery signal transmission and detection request.

The parent node transmits a discovery signal transmission and detectionrequest to the child node (S1630).

The child node performs discovery signal transmission and detection(S1640).

The child node transmits discovery signal detection feedback to theparent node (S1650). Here, the discovery signal detection feedback maybe a signal aperiodically transmitted.

A detailed description of each step in FIG. 16 is the same as describedabove, and thus a redundant description thereof will be omitted.

Next, discovery signal transmission timing will be described.

Specifically, timing at which a node actually transmit a discoverysignal when receiving a discovery signal transmission and detectionrequest and timing at which other nodes are expected to transmit adiscovery signal will be described. The discovery signal transmissionand detection request may refer to a discovery request in transmissionand reception of a discovery signal for detection and measurement, whichwill be described later. In the following description, a subframe may bereplaced with a slot, a mini-slot, or a symbol.

[Method A]

When a node receives a discovery signal transmission and feedbackrequest in subframe n (or slot n), the node may transmit a discoverysignal in subframe (or slot) n+K. Here, K may be a value differently setfor each node. K may be transmitted via a discovery signal transmissionconfiguration or a different RRC message. K for each node with respectto a discovery signal transmitted by other nodes may be transmittedthrough a discovery signal detection setting or a different RRC message.Alternatively, K for each node may be a value determined on the basis ofthe cell ID (or node ID), the number of hops from a DgNB to the node, orthe like.

[Method B]

When a node receives a discovery signal transmission and feedbackrequest in subframe n, the node transmits a discovery signal in subframen+K+K′. Here, a subframe may be replaced with a slot/mini-slot.

K may be a value set equally or differently for each node. K may bespecified in the specification or may be transmitted via the request fordiscovery signal transmission and feedback. Alternatively, K may be avalue separately set by RRC or the like.

K′ may be a value that is differently set for each node to change thetiming of each node transmitting a discovery signal. K′ for a particularnode with respect to a discovery signal transmitted by the particularnode may be transmitted through a discovery signal transmissionconfiguration or a different RRC message. K′ for each node with respectto a discovery signal transmitted by other nodes may be transmittedthrough a discovery signal detection setting or a different RRC message.

Alternatively, K′ for each node may be a value determined on the basisof the cell ID (or node ID), the number of hops from a DgNB to the node,an even/odd hop, (hope count) % K, or the like.

FIG. 17 schematically illustrates an example in which discovery signaltransmission timing is applied according to the disclosure.

Specifically, (a) of FIG. 17 illustrates an example in which method Afor discovery signal transmission timing is applied. Referring to (a) ofFIG. 7, a node transmits a discovery signal after K subframes from thetime when a discovery signal transmission and detection request isreceived.

Further, (b) of FIG. 17 illustrates an example in which method B fordiscovery signal transmission timing is applied. Referring to (b) ofFIG. 7, a node transmits a discovery signal after K+K′ subframes fromthe time when a discovery signal transmission and detection request isreceived.

Although FIG. 17 illustrates an example in which a discovery signaltransmission and detection request is received, the foregoing methodsmay also be applied when a discovery signal transmission and feedbackrequest is received. In addition, since a detailed description of (a)and (b) of FIG. 17 has been made above, a redundant description isomitted.

[Method C]

Although a discovery signal is not periodically transmitted, there maybe a period and an offset for transmission of a discovery signal. Aposition at which a discovery signal can be transmitted may bedetermined according to this period and offset. A node does not normallytransmit a discovery signal but may transmit a discovery signal at thenearest discovery signal transmission timing after subframe n+K whenreceiving a discovery signal transmission and feedback request insubframe n.

K may be specified in the specification or may be transmitted via thediscovery signal transmission and feedback request. Alternatively, K maybe a value separately set by RRC or the like.

FIG. 18 schematically illustrates another example in which discoverysignal transmission timing is applied according to the disclosure.Specifically, FIG. 18 illustrates an example in which method C fordiscovery signal transmission timing is applied.

In FIG. 18, the timing at which a discovery signal can be transmitted isindicated in a dotted line. At this timing, a node does not actuallytransmit a discovery signal. When receiving a discovery signaltransmission and feedback request, the node actually transmits adiscovery signal at the nearest timing at which a discovery signal canbe transmitted after subframe K.

Although FIG. 18 illustrates an example in which a discovery signaltransmission and detection request is received, the same method may alsobe applied when a discovery signal transmission and feedback request isreceived.

[Method D]

When a node receives a discovery signal transmission and feedbackrequest in subframe n (or slot n), the node may recognize duration forwhich a discovery signal is transmitted from subframe n+K as an intervalduring which the discovery signal can be transmitted. Here, K and/ordiscovery duration may be set through a discovery signal transmissionand feedback request message, may be set in advance through RRC, DCI, orthe like, or may be defined in the specification. An IAB node may derivethe timing at which the IAB node actually transmits a discovery signalwithin the interval during which the discovery signal can betransmitted. For example, it may be considered to configure the startpoint of a discovery signal (subframe number (SFN)=i), duration (40 ms),a method for configuring a discovery signal occasion within the duration(e.g., repetition of DDXX (i.e., repetition of two D slots+two X slots,where a D slot may refer to a downlink slot and an X slot may refer to aflexible slot), in which it is assumed that only two slots are used totransmit the discovery signal every four slots from the start point), amethod for determining transmission timing for each RN (e.g.,transmission timing is determined according to aneven-numbered/odd-numbered hop), or the like.

Hereinafter, proposed is transmission and reception of a discoverysignal for detection/measurement to enable IAB nodes to recognize eachother and to measure the channel condition.

Hereinafter, in the disclosure, a signal that IAB nodes transmit orreceive to recognize each other or to detect the best TX-RX beam pair(s)may be referred to as discovery signal A or a detection signal, and asignal for measuring the channel condition with respect to each othermay be referred to as discovery signal B or a measurement signal. Here,each of discovery signal A and discovery signal B may be a signal newlydefined for the IAB nodes to transmit and receive in order to recognizeeach other or to detect the best TX-RX beam pair(s). Here, in oneexample, a discovery signal may be newly defined in a manner of reusingan existing SSB. Further, a discovery signal may also be a backhaul-SSBdescribed above.

Discovery signal A and discovery signal B may be defined to bedistinguished from each other or may be defined to be identical to eachother. That is, discovery signal A and discovery signal B are defineddifferently such that discovery signal A may be used for detection of anIAB node, and discovery signal B may be used for measurement.Alternatively, discovery signal A and discovery signal B may be definedas one signal and may be used for both detection and measurement.

Discovery signal A and discovery signal B may have the followingcharacteristics.

First, the characteristics of discovery signal A are described.

Discovery signal A may be a signal transmitted for an IAB node to detectanother IAB node and/or a beam direction. Discovery signal A fordetecting IAB nodes may be transmitted in all beam directions (i.e.,omnidirectionally) or in various beam directions because the location ofa node is highly unlikely to be recognized at all or exactly. Further,in an environment where an IAB node has little mobility, a change in theconfiguration of IAB nodes rarely occurs. Therefore, it is not necessaryto frequently perform an IAB node detection process, and thus it is notnecessary to frequently transmit discovery signal A.

IAB nodes may not know accurate information about synchronizationbetween each other and may thus need to perform time/frequencysynchronization using discovery signal A. Considering thecharacteristics of the discovery signal, it may be effective to reuse oruse an SSB as discovery signal A. As the SSB, an SSB transmitted by eachnode in an access link may be shared for use.

When synchronization between IAB nodes is achieved to some extent, itmay be unnecessary to perform synchronization using discovery signal A.In this case, discovery signal A may have the same form as a CSI-RS, aTRS, a PDSCH, a D2D discovery signal, and the like.

Next, the characteristics of discovery signal B are described.

Discovery signal B is a signal transmitted to measure the continuouschannel condition for a significant IAB node and/or a beam directionselected through a detection process. Assuming that an IAB node hardlyhas mobility, a beam direction for transmission to a particular nodedoes not change. Therefore, the IAB node may perform measurement only inthe direction of particular/some beams transmitted to the IAB node, anddiscovery signal B may also be transmitted only in the direction ofparticular/some beams in which the IAB node exists. Since the quality ofa channel needs to be continuously measured, it is necessary toperiodically transmit discovery signal B and to perform measurement.Considering the characteristics of discovery signal B, when ameasurement period is so long as to cause significant synchronizationdeviation, it may be necessary to reuse or use the form of an SSB. Whena measurement period is short and thus synchronization deviation doesnot significantly occur until measurement is performed again, it may bepreferable to reuse/use the form of a CSI-RS or another referencesignal.

Particularly, discovery signal B may be transmitted via an access linkand may be shared with a CSI-RS that a UE transmits via the access linkto perform measurement.

The difference between discovery signal A and discovery signal B may beas follows.

-   -   Discovery signal A may have a structure of sweeping a        transmission beam to be used by each node in a backhaul. In the        case of discovery signal B, however, only a subset of a        plurality of transmission beams may be transmitted.    -   Discovery signal A may be transmitted on the basis of broadcast        to an unspecified node. Therefore, it may be assumed that when        each node needs reception beam sweeping, repetition for        reception beam sweeping is performed for each transmission beam.    -   FDM/SDM/CDM may be taken into consideration in order to reduce        overall time to transmit a discovery signal between nodes. TDM        between nodes may also be considered. For example, when TDM is        performed according to a hop count, resources may be divided by        FDM between nodes sharing each hop count. Frequency resources        used by each node may be changed over time or may randomly be        selected for randomization of an interference level or the like.        For example, when discovery signal A is configured on the basis        of a CSI-RS, a mapping resource element (mapping RE) may be        different for each node, or a CSI-RS transmission frequency        region/bandwidth may be set differently. Alternatively,        time/frequency resources may be determined according to the node        ID, in which the node ID may be assumed to be set by a DgNB.

Considering the characteristics of discovery signal A and discoverysignal B described above, a process for detecting and measuring IABnodes may be performed as follows.

First, a method of transmitting and receiving a discovery signal may beperformed as follows.

[Method 1] Simultaneous Detection and Measurement

For example, discovery signal A and discovery signal B may be definedand transmitted as one signal, or discovery signal A and discoverysignal B may always be transmitted together. Here, discovery signal Aand discovery signal B may be transmitted periodically or aperiodicaly,and an IAB node detection and measurement process may also be performedperiodically or aperiodically.

When a discovery signal is transmitted and received in this manner, aprocess for detecting and measuring an IAB node through the discoverysignal may be performed as follows. Here, all or part of the followingprocess may be included.

(Step 1) Reception of Discovery Signal-Related Configuration

An IAB node needs to know configurations about discovery signal A anddiscovery signal B required to transmit a discovery signal and toperform detection and measurement using a discovery signal transmittedby other nodes. These configurations may follow details proposed fordiscovery signal configurations among specific details of aconfiguration for transmission and reception of a discovery signal to bedescribed later. Here, discovery signal A and discovery signal B may bedefined as one signal.

(Step 2) Reception of Discovery Request

When a discovery signal is aperiodically transmitted, the IAB node mayreceive a discovery request message in order to know the time totransmit a discovery signal and to perform detection and measurement byreceiving a discovery signal from other nodes. Even when a discoverysignal is periodically transmitted, a discovery request message may betransmitted to indicate the time to start and/or terminate a discoveryprocess. The discovery request message may be received from a parentnode. Upon receiving this message, the node may know the time totransmit a discovery signal and/or the time to perform detection andmeasurement using a discovery signal transmitted by other nodes. Here,details about transmission and reception of a discovery request messageand the time to transmit a discovery signal after receiving thediscovery request message and to perform detection and measurement ofanother node may follow details proposed for a discovery request amongthe specific details of the configuration for transmission and receptionof the discovery signal to be described later.

(Step 3) IAB Detection and Measurement

The IAB node transmits a discovery signal that the IAB node needs totransmit and/or performs detection and measurement using a discoverysignal transmitted by other nodes at the time determined or setaccording to (Step 1) and/or (Step 2).

(Step 4) Discovery Feedback

After performing the detection and the measurement, the IAB node feedsback the result to the parent node. The time to transmit feedbackinformation may be defined or may be set in advance. Here, the time atwhich the IAB node feeds back the detection result and/or themeasurement result and information included in the feedback may followdetails proposed for discovery feedback among the specific details ofthe configuration for transmission and reception of the discovery signalto be described later.

[Method 2] Semi-Persistent Measurements

After detecting an IAB node through discovery signal A, a process ofmeasuring a particular IAB node and a beam direction once orperiodically a plurality of times may be performed as one set.

FIG. 19 illustrates a process of discovering and measuring an IAB nodethrough a discovery signal according to the disclosure.

Referring to FIG. 19, discovery signal A is transmitted, and thendiscovery signal B is sequentially transmitted five times. Here,discovery signal B is transmitted five times with a period of DS B. Inaddition, discovery signal A and five discovery signals B may be definedas a discovery signal set.

A reception node receiving discovery signal A and discovery signal B mayperform detection and measurement operations of discovery signal A anddiscovery signal B, respectively, and may transmit feedback informationabout each of the detection and measurement operations to a parent nodeof the reception node. Here, detection feedback information includingthe detection result about discovery signal A may be aperiodicallytransmitted, and measurement feedback information including themeasurement result about discovery signal B may be periodicallytransmitted.

Although FIG. 19 illustrates only an example in which discovery signal Bis repeatedly transmitted five times, which is only for illustration,and various discovery signal sets may be configured.

That is, when an IAB node performs a process for discovering another IABnode, as shown in FIG. 19, detection of an IAB node is performed throughdiscovery signal A transmitted first, and then measurement of a selectedIAB node(s) and/or beam direction(s) is periodically performed on thebasis of the detection result through discovery signal B repeatedlytransmitted. Here, in the disclosure, discovery signal A transmittedfirst and discovery signal B subsequently transmitted are collectivelyreferred to as a discovery signal set, and discovery signal B isperiodically transmitted with a period of DS B. The discovery signal setmay be transmitted aperiodically or periodically.

When a discovery signal is transmitted and received in this manner, aprocess for detecting and measuring an IAB node through the discoverysignal may be performed as follows. Here, all or part of the followingprocess may be included.

(Step 1) Reception of Discovery Signal A-Related Configuration

An IAB node may need to know configurations required to transmitdiscovery signal A and to perform detection by receiving discoverysignal A transmitted by other nodes. These configurations may follow thedetails proposed for the discovery signal configurations among thespecific details of the configuration for transmission and reception ofthe discovery signal to be described later.

(Step 2) Reception of Discovery Signal B-Related Configuration

An IAB node may need to know configurations required to transmitdiscovery signal B and to perform measurement by receiving discoverysignal B transmitted by other nodes. These configurations may follow thedetails proposed for the discovery signal configurations among thespecific details of the configuration for transmission and reception ofthe discovery signal to be described later.

In the disclosure, these configurations may be set together with thediscovery signal A-related configurations proposed above in (Step 1).

(Step 3) Reception of Discovery Request

When a discovery signal set is aperiodically transmitted, a discoveryrequest message may be transmitted in order to indicate the time totransmit a discovery signal set and the time to perform detection andmeasurement of other nodes. That is, the IAB node may receive thediscovery request message from a parent node, and may know the time totransmit discovery signal A and/or the time to perform IAB nodedetection by receiving discovery signal A from other nodes uponreceiving the message. Here, details about transmission and reception ofa discovery request message and the time to transmit discovery signal Aafter receiving the discovery request message and to perform detectionof another node may follow details proposed for a discovery requestamong the specific details of the configuration for transmission andreception of the discovery signal to be described later.

(Step 4) IAB Detection

The IAB node may transmit discovery signal A that the IAB node needs totransmit and/or may perform IAB node detection using discovery signal Atransmitted by other nodes at the time determined or set according to(Step 1) and/or (Step 3).

(Step 5) IAB Detection Feedback

After performing the detection, the IAB node feeds back the result tothe parent node. The time to transmit feedback information may bedefined or may be set in advance. Here, the time at which the IAB nodefeeds back the detection result and information included in the feedbackmay follow details proposed for discovery feedback among the specificdetails of the configuration for transmission and reception of thediscovery signal to be described later.

(Step 6) Reception of Discovery Signal B-Related Configuration and IABMeasurement

After feeding back the result of the detection using discovery signal A,the IAB node may receive, from the parent node, a transmission-relatedconfiguration of discovery signal B, and/or a node and a beam directionto be subjected to IAB node measurement, and/or a timing-relatedconfiguration. These configurations may follow the details proposed forthe discovery signal configurations among the specific details of theconfiguration for transmission and reception of the discovery signal tobe described later. This step of receiving the discovery signalB-related configuration (Step 6) may be an additional step.

(Step 7) IAB Measurement

The IAB node may transmit discovery signal B that the IAB node needs totransmit and/or may perform IAB node measurement using discovery signalB transmitted by other nodes at the time determined or set according to(Step 2) and/or (Step 6).

(Step 8) IAB Measurement Feedback

After performing the measurement, the IAB node feeds back the result tothe parent node. The time to transmit feedback information may bedefined or may be set in advance. Here, the time at which the IAB nodefeeds back the measurement result and information included in thefeedback may follow details proposed for discovery feedback among thespecific details of the configuration for transmission and reception ofthe discovery signal to be described later.

[Method 3] Periodic Detection and Measurement According to DifferentPeriods

IAB node detection using discovery signal A and IAB node measurementusing discovery signal B may be periodically performed, but withdifferent periods. That is, transmission of discovery signal A and/orIAB node detection may be performed with a discovery signal A period,and transmission of discovery signal B and/or IAB node measurement maybe performed with a discovery signal B period. Here, the discoverysignal A period may be set to be greater than the discovery signal Bperiod.

When a discovery signal is transmitted and received in this manner, aprocess for detecting and measuring an IAB node through the discoverysignal may be performed as follows. Here, all or part of the followingprocess may be included.

(Step 1) Reception of Discovery Signal A-Related Configuration

An IAB node needs to know configurations required to transmit discoverysignal A and to perform detection by receiving discovery signal Atransmitted by other nodes. These configurations may follow the detailsproposed for the discovery signal configurations among the specificdetails of the configuration for transmission and reception of thediscovery signal to be described later.

(Step 2) Reception of Discovery Signal B-Related Configuration

An IAB node needs to know configurations required to transmit discoverysignal B and to perform measurement by receiving discovery signal Btransmitted by other nodes. These configurations may follow the detailsproposed for the discovery signal configurations among the specificdetails of the configuration for transmission and reception of thediscovery signal to be described later. In the disclosure, theseconfigurations may be set together with the discovery signal A-relatedconfigurations proposed above in (Step 1).

(Step 3) Reception of Discovery Request

When a discovery signal is periodically transmitted, a discovery requestmessage may also be transmitted for the IAB node to know the time toactually start a discovery process and/or the time to terminate thediscovery process. That is, the IAB node may receive the discoveryrequest message from a parent node, and may know the time to startand/or terminate transmission of a discovery signal and the time toperform IAB node detection and measurement by receiving a discoverysignal from other nodes upon receiving the message. Here, details abouttransmission and reception of a discovery request message and the timeto transmit a discovery signal after receiving the discovery requestmessage and to perform detection and measurement of another node mayfollow details proposed for a discovery request among the specificdetails of the configuration for transmission and reception of thediscovery signal to be described later.

(Step 4) IAB Detection

The IAB node may transmit discovery signal A that the IAB node needs totransmit and/or may perform IAB node detection using discovery signal Atransmitted by other nodes at the time determined or set according to(Step 1).

(Step 5) IAB Detection Feedback

After performing the detection, the IAB node feeds back the result tothe parent node. The time to transmit feedback information may bedefined or may be set in advance. Here, the time at which the IAB nodefeeds back the detection result and information included in the feedbackmay follow details proposed for discovery feedback among the specificdetails of the configuration for transmission and reception of thediscovery signal to be described later.

(Step 6) Reception of Discovery Signal B-Related Configuration

After feeding back the result of the detection using discovery signal A,the IAB node may receive, from the parent node, a transmission-relatedconfiguration of discovery signal B, and/or a node and a beam directionto be subjected to IAB node measurement, and/or a timing-relatedconfiguration. These configurations may follow the details proposed forthe discovery signal configurations among the specific details of theconfiguration for transmission and reception of the discovery signal tobe described later. This step may be an additional step.

(Step 7) IAB Measurement

The IAB node may transmit discovery signal B that the IAB node needs totransmit and/or may perform IAB node measurement using discovery signalB transmitted by other nodes at the time determined or set according to(Step 2) and/or (Step 5).

(Step 8) IAB Measurement Feedback

After performing the measurement, the IAB node feeds back the result tothe parent node. The time to transmit feedback information may bedefined or may be set in advance. Here, the time at which the IAB nodefeeds back the measurement result and information included in thefeedback may follow details proposed for discovery feedback among thespecific details of the configuration for transmission and reception ofthe discovery signal to be described later.

[Method 4] Aperiodic Detection and Periodic Measurement

Since an IAB node may generally have the characteristics of a staticnode, the IAB node may be relatively rarely detected via discoverysignal A. Further, an SSB of NR has relatively larger signal overheadthan a synchronization signal of LTE. Thus, for example, when an NR SSBis reused for discovery signal A and detection of an IAB node throughdiscovery signal A is periodically performed, inefficiency in usingresources, power, or the like may be incurred. Furthermore, in ahigh-frequency band, detection in all beam directions may result inexcessive overhead.

Therefore, IAB node detection using discovery signal A may be performedaperiodically and intermittently, while IAB measurement using discoverysignal B, which needs not to be continuously performed, may be performedperiodically. That is, when the IAB node discovers another IAB node, theIAB node may aperiodically and intermittently perform IAB node detectionusing discovery signal A and may then periodically perform, usingdiscovery signal B repeatedly transmitted, measurement of an IAB node(s)and/or beam direction(s) selected on the basis of the detection result.

When a discovery signal is transmitted and received in this manner, aprocess for detecting and measuring an IAB node through the discoverysignal may be performed as follows. Here, all or part of the followingprocess may be included.

(Step 1) Reception of Discovery Signal A-Related Configuration

An IAB node needs to know configurations required to transmit discoverysignal A and to perform detection by receiving discovery signal Atransmitted by other nodes. These configurations may follow the detailsproposed for the discovery signal configurations among the specificdetails of the configuration for transmission and reception of thediscovery signal to be described later.

(Step 2) Reception of Discovery Signal B-Related Configuration

An IAB node needs to know configurations required to transmit discoverysignal B and to perform measurement by receiving discovery signal Btransmitted by other nodes. These configurations may follow the detailsproposed for the discovery signal configurations among the specificdetails of the configuration for transmission and reception of thediscovery signal to be described later. In the disclosure, theseconfigurations may be set together with the discovery signal A-relatedconfigurations proposed above in (Step 1).

(Step 3) Reception of Discovery Request

When discovery signal A is periodically transmitted, a discovery requestmessage may be transmitted for the IAB node to know the time to transmitdiscovery signal A and to perform detection of other nodes. That is, theIAB node may receive the discovery request message from a parent node,and may know the time to transmit discovery signal A and/or the time toperform IAB node detection by receiving discovery signal A from othernodes upon receiving the message. Here, details about transmission andreception of a discovery request message and the time to transmitdiscovery signal A after receiving the discovery request message and toperform detection of another node may follow details proposed for adiscovery request among the specific details of the configuration fortransmission and reception of the discovery signal to be describedlater.

(Step 4) IAB Detection

The IAB node may transmit discovery signal A that the IAB node needs totransmit and/or may perform IAB node detection using discovery signal Atransmitted by other nodes at the time determined or set according to(Step 1) and/or (Step 3).

(Step 5) IAB Detection Feedback

After performing the detection, the IAB node feeds back the result tothe parent node. The time to transmit feedback information may bedefined or may be set in advance. Here, the time at which the IAB nodefeeds back the detection result and information included in the feedbackmay follow details proposed for discovery feedback among the specificdetails of the configuration for transmission and reception of thediscovery signal to be described later.

(Step 6) Reception of Discovery Signal B-Related Configuration

After feeding back the result of the detection using discovery signal A,the IAB node may receive, from the parent node, a transmission-relatedconfiguration of discovery signal B, and/or a node and a beam directionto be subjected to IAB node measurement, and/or a timing-relatedconfiguration. These configurations may follow the details proposed forthe discovery signal configurations among the specific details of theconfiguration for transmission and reception of the discovery signal tobe described later.

(Step 7) IAB Measurement

The IAB node may transmit discovery signal B that the IAB node needs totransmit and/or may perform IAB node measurement using discovery signalB transmitted by other nodes at the time determined or set according to(Step 2) and/or (Step 5).

(Step 8) IAB Measurement Feedback

After performing the measurement, the IAB node feeds back the result tothe parent node. The time to transmit feedback information may bedefined or may be set in advance. Here, the time at which the IAB nodefeeds back the measurement result and information included in thefeedback may follow details proposed for discovery feedback among thespecific details of the configuration for transmission and reception ofthe discovery signal to be described later.

FIG. 20 schematically illustrates an example of a method for aperiodicdetection and periodic measurement of an IAB node according to thedisclosure.

Referring to FIG. 20, discovery signal B is periodically transmittedwith a discovery signal B period, and discovery signal A isaperiodically transmitted.

As described above, [Method 4] may be applied as a method for aperiodicdetection and periodic measurement of an IAB node. Since a detaileddescription of the method has been described above, a redundantdescription is omitted.

A node may receive a configuration about whether transmission anddetection of discovery signal A is performed periodically oraperiodically. Furthermore, as described above, since detection in allbeam directions may cause excessive overhead to an IAB node, detectionmay be performed only in specific beam directions depending on theconfiguration. This configuration may be transmitted via systeminformation or RRC.

Particularly, both periodic detection and aperiodic detection may beperformed. That is, periodic detection and aperiodic detection may beperformed in parallel. In this case, a discovery signal A configurationfor periodic detection and a discovery signal A configuration foraperiodic detection may be set separately.

Alternatively, a plurality of discovery signal A configurations may beset, each of which may be a configuration for periodic detection or aconfiguration for aperiodic detection. When a plurality of discoverysignal A configurations is set for periodic detection, a detectionperiod and/or a detection offset may vary.

In the foregoing description, a detection operation may be construed asbeing replaced with an operation of transmitting discovery signal A. Theforegoing description may also be applied to transmission andmeasurement of discovery signal A.

Hereinafter, a configuration for transmission and reception of adiscovery signal will be described in detail.

First, discovery signal configurations among details of theconfiguration for the transmission and reception of the discovery signalwill be described.

A parent node may determine configurations related to transmission of adiscovery signal and detection/measurement using the discovery signalfor a child node. Alternatively, a DgNB may determine and report theseconfigurations each node associated therewith. In this case, the parentnode may forward configuration information, received from the DgNB, tothe child node. In addition, a configuration associated withtransmission of discovery signal A (discovery signal A configuration)may be transmitted semi-statically through RRC, system information, orthe like.

The discovery signal A configuration may include the followinginformation.

-   -   Periodic or aperiodic detection: It may be set whether to        periodically or aperiodically perform transmission of discovery        signal A and IAB detection.    -   Discovery signal A transmission period: When discovery signal A        is periodically transmitted, an IAB node may receive a period of        discovery signal A that the IAB node transmits.    -   Discovery signal A transmission offset: There may be a timing        offset between discovery signals A transmitted by different IAB        nodes in order to efficiently utilize resources or to reduce        interference in transmission of discovery signal A between IAB        nodes. This offset may be determined according to an IAB node        ID, a hop level (i.e., the number of hops from a donor node),        information about a path from the donor node, and/or a specific        value (e.g., α) set by the parent node (to distinguish nodes in        the same hop level). Accordingly, the IAB node may receive a set        offset value for discovery signal A that the IAB node transmits        or a set value (e.g., α) necessary to determine the offset value        for discovery signal A.    -   Discovery signal A beam direction list: When transmitting        discovery signal A, the IAB node may transmit discovery signal A        only in a beam direction in which an IAB node may exist. For        example, when recognizing that other IAB nodes are not located        at a lower position, the IAB node may transmit discovery signal        A in a direction other than the direction of the position.        Accordingly, the direction of a transmission beam used for        transmission of discovery signal A may be limited to some        directions, thereby reducing the overhead of the IAB node for        discovery signal A transmission. To this end, a transmission        beam direction(s) used for transmission of another discovery        signal A may be set.    -   IAB detection period: When the IAB node periodically detects        discovery signal A, a discovery signal A detection period may be        set. In particular, the period may always be the same as a        discovery signal A transmission period with which the IAB node        transmits discovery signal A. Alternatively, the IAB node may        have a plurality of (e.g., two) discovery signal A detection        periods. In this case, IAB node detection may be performed at        both the time determined according to a first period and the        time determined according to a second period.    -   IAB detection duration: This information indicates duration        during which the IAB node attempts IAB detection. The length of        the duration may be defined in the specification or may be set        by the parent node. Particularly, when set, the duration may be        set for each IAB detection period. Here, it may be assumed that        the IAB node performs detection at the time when the IAB node        does not transmit a discovery signal in an IAB detection        interval. In this case, each RN may not accurately know which        node transmits a discovery signal at which time in the IAB        detection interval.    -   IAB detection node list: To help the IAB node in detecting a        neighboring IAB node, cell ID (or node ID) information of the        neighboring IAB node may be provided. That is, the cell ID (or        node ID) of an IAB node (s) that the IAB node needs to detect        may be set. In this case, the IAB node is required to detect        only IAB nodes included in the IAB node list. Alternatively,        even though an IAB node list is set, IAB nodes to be detected by        the IAB node may not be limited to IAB nodes in the set list. In        particular, when there is a plurality of discovery signal A        detection periods, an IAB node list may be set for each        discovery signal A detection period. That is, it is possible to        know which discovery signal A detection period each IAB node        included in the IAB node list has.    -   Reception beam list: The direction of a reception beam used for        the IAB node to detect another IAB node may be limited to some        reception beam directions, thereby reducing the overhead of the        IAB node for detection. To this end, a reception beam        direction(s) used for detection of another node may be set.

A configuration associated with transmission of discovery signal B(discovery signal B configuration) may also be transmittedsemi-statically through RRC, system information, or the like. Thediscovery signal B configuration may include the following information.

-   -   Discovery signal B transmission period: When discovery signal B        is periodically transmitted, an IAB node may receive a period of        discovery signal B that the IAB node transmits.    -   Discovery signal B transmission offset: There may be a timing        offset between discovery signals B transmitted by different IAB        nodes in order to efficiently utilize resources or to reduce        interference in transmission of discovery signal B between IAB        nodes. This offset may be set to the index of a slot/index of a        subframe in which discovery signal B is transmitted. This offset        may be determined according to an IAB node ID, a hop level        (i.e., the number of hops from a donor node), information about        a path from the donor node, and/or a specific value (e.g., (3)        set by the parent node (to distinguish nodes in the same hop        level). Accordingly, the IAB node may receive a set offset value        for discovery signal B that the IAB node transmits or a set        value (e.g., (3) necessary to determine the offset value for        discovery signal B.    -   Discovery signal B transmission resource index: For example,        when discovery signal B is a type such as a CSI-RS, discovery        signal B may be transmitted through one resource or a plurality        of resources among a plurality of resources for transmitting        discovery signal B. In this case, index information indicating        the position of a resource through which the IAB node transmits        discovery signal B may be set.    -   Discovery signal B beam direction index: An analog beam        direction index and/or a precoding index for which the IAB node        transmits discovery signal B may be set. In this case, the        analog beam direction index and/or the precoding index may be        set for each discovery signal B transmission resource index.    -   IAB measurement period: When the IAB node periodically performs        measurement using discovery signal B, a discovery signal B        measurement period may be set. In particular, the period may        always be the same as a discovery signal B transmission period        with which the IAB node transmits discovery signal B.        Alternatively, the IAB node may have a plurality of (e.g., two)        discovery signal B measurement periods. In this case, IAB node        measurement may be performed at both the time determined        according to a first period and the time determined according to        a second period.    -   IAB measurement duration: This information may indicate duration        during which the IAB node performs IAB measurement. The length        of the duration may be defined in the specification or may be        set by the parent node. Particularly, when set, the IAB        measurement duration may be set for each IAB measurement period.        Here, it may be assumed that the IAB node performs measurement        at the time when the IAB node does not transmit a discovery        signal in an IAB measurement interval. In this case, each RN may        not accurately know which node transmits a discovery signal at        which time in the IAB measurement interval.    -   IAB measurement list: The IAB node may perform measurement using        discovery signals B transmitted by a plurality of IAB nodes.        Further, the IAB node may perform measurement on a plurality of        discovery signal B resources transmitted by one IAB node. Here,        the following information may be set for each discovery signal B        resource (IAB measurement resource) on which the IAB node needs        to perform measurement.    -   Cell ID (or node ID)    -   IAB measurement period    -   IAB measurement offset: Timing offset for which the IAB node        performs measurement    -   Discovery signal B resource index

Characteristically, as described above, instead of setting a measurementperiod for each resource for which the IAB node performs measurement, adiscovery signal B resource belonging to a specific measurement periodmay be defined.

Characteristically, the discovery signal B configuration may be set intwo steps. As in [Method B] to [Method D] for the method fortransmitting and receiving the discovery signal, some information may beset in advance, and some information may be additionally set afterperforming IAB node detection and feeding back the result, because anIAB node and a beam direction for measurement may vary depending on thedetection result.

When detection/measurement of an IAB node is periodically performed,detection/measurement of an IAB node may be performed without anyrequest message after receiving a discovery signal configuration. Inthis case, the detection/measurement of the IAB node may be performedusing a discovery signal transmitted after receiving the discoverysignal configuration.

This configuration may be for setting the timing at which each DgNB/RNstarts transmitting a discovery signal, during, a set of discoverysignal transmission occasions within that duration, and/or a method foreach RN to determine a discovery signal occasion. For example, it may beconsidered to configure the start point of a discovery signal (SFN=i),duration (40 ms), a method for configuring a discovery signal occasionwithin the duration (e.g., repetition of DDXX (i.e., repetition of two Dslots+two X slots), in which it is assumed that only two slots are usedto transmit the discovery signal every four slots from the start point),a method for determining discovery signal transmission timing for eachRN (e.g., transmission timing is determined according to aneven-numbered/odd-numbered hop), or the like.

Characteristically, the IAB node may receive a plurality of discoverysignal configurations as described above. For example, the IAB node mayreceive one or a plurality of configuration sets for transmission of adiscovery signal and may receive one or a plurality of configurationsets for detection/measurement through the discovery signal.Alternatively, the IAB node receives one or a plurality of configurationsets for transmission of discovery signal A and/or one or a plurality ofconfiguration sets for transmission of discovery signal B and mayreceive one or a plurality of configuration sets for IAB node detectionand/or one or a plurality of configuration sets for IAB nodemeasurement. In this case, a procedure for transmission anddetection/measurement of a discovery signal may be aperiodicallytriggered according to a dynamic request. Here, when an aperiodicrequest (by discovery request message) is made, one of the plurality ofconfiguration sets received in advance may be selectively requested.That is, a plurality of discovery operations, such as a full discoverymode in which transmission is performed with all transmission beams anda partial discovery mode in which transmission is performed only withbeams associated with a child node, may be configured according to achange in network topology, one among which may be selectivelydesignated.

Hereinafter, a discovery request among the details of the configurationfor the transmission and reception of the discovery signal will bedescribed.

When a discovery signal is transmitted periodically or aperiodically, adiscovery request message may be transmitted to request detection and/ormeasurement using the discovery signal. Here, when the discovery requestmessage is used, when an IAB node may perform IAB node detectionand/measurement using the discovery signal upon receiving the discoveryrequest message.

This request may be determined by a parent node and may be configuredfor a child node. Alternatively, a DgNB may determine and report theseconfigurations to each node associated therewith. In this case, theparent node may forward this request information received from the DgNBto the child node. This request may be transmitted via message 4 (Msg4), RRC, and/or a PDCCH (DCI). Since transmission and reception of adiscovery signal needs to be performed by a plurality of nodes together,this request may be transmitted through cell-specific or group-specificRRC or PDCCH (DCI). Alternatively, this request may be transmitted to anRN associated with the DgNB via RRC through each path.

When a discovery signal is aperiodically transmitted, the time at whichthe IAB node transmits a discovery signal and performs detection and/ormeasurement after receiving a discovery request message may be asfollows.

-   -   When the IAB node receives a discovery request in subframe n (or        slot n), the node may transmit a discovery signal in subframe        n+K (or slot n+K). K may be defined as a specific value in the        specification or may be a value set by the parent node.        Characteristically, defining a discovery signal A transmission        offset for node x as K′_x, when the IAB node receives a        discovery request in subframe n (or slot n), the node may        transmit discovery signal A in subframe n+K+K′_n (or slot        n+K+K′_n). Alternatively, when the IAB node receives a discovery        request in subframe n (or slot n), the node performs detection        for IAB detection duration from subframe n+K (or slot n+K). This        description may be applied not only to a case of performing IAB        detection with discovery signal A but also to a case of        performing IAB measurement with discovery signal B.    -   Although a discovery signal is actually aperiodically        transmitted, there may be a period and an offset for        transmission of a discovery signal. A position at which a        discovery signal can be transmitted may be determined according        to this period and offset. A node does not normally transmit a        discovery signal but may transmit a discovery signal at the        nearest discovery signal transmission timing after subframe n+K        (or slot n+K) when receiving a discovery request in subframe n        (or slot n). Further, although a discovery signal is actually        aperiodically transmitted, a time region for transmitting        detection with discovery signal A may be determined according to        an IAB detection period. In this case, when the IAB node        receives a discovery request in subframe n (or slot n), the node        may perform detection for IAB detection duration at the nearest        time for performing IAB detection after subframe n+K (or slot        n+K).

This description may be applied not only to a case of performing IABdetection with discovery signal A but also to a case of performing IABmeasurement with discovery signal B.

When a discovery signal is periodically transmitted, the time at whichthe IAB node first transmits a discovery signal and performs detectionand/or measurement after receiving a discovery request message may be asfollows.

-   -   When receiving a discovery request in subframe n (or slot n),        the node may transmit discovery signal A at a discovery signal A        transmission time according to a transmission period and an        offset for discovery signal A after subframe n+K (or slot n+K).        Further, when a discovery signal is periodically transmitted and        thus IAB detection is periodically performed, if the IAB node        receives a discovery request in subframe n (or slot n), the node        may perform IAB detection according to an IAB detection period        and duration after subframe n+K (or slot n+K).

This description may be applied not only to a case of performing IABdetection with discovery signal A but also to a case of performing IABmeasurement with discovery signal B.

When a discovery request message is transmitted, all or some informationof the foregoing discovery signal configurations may be included andtransmitted.

Characteristically, when a discovery request message is transmitted, itmay be configured whether the node performs only transmission ofdiscovery signal A without detection, performs detection only withouttransmission of discovery signal A, or performs both transmission ofdiscovery signal A and detection. Depending on this configuration, thenode may only transmit discovery signal A without detecting aneighboring node, may only detect a neighboring node withouttransmitting discovery signal A, or may perform both transmission ofdiscovery signal A and detection. This description may equally beapplied to transmission of discovery signal B and measurement.

Hereinafter, discovery feedback among the details of the configurationfor the transmission and reception of the discovery signal will bedescribed.

After performing IAB detection using discovery signal A, the JAB nodeperforms JAB detection feedback of feeding back the detection result tothe parent node or the DgNB. The feedback may be transmitted via a PUCCHand/or a PUSCH. Here, feedback information may include the followingdetails.

-   -   Detected IAB node ID and beam ID: The ID of an IAB node        successfully detected by the IAB node and/or a beam ID are        transmitted. Here, the beam ID may refer to the index of an        SS/PBCH block. The number of IAB nodes or the number of {JAB        node ID, beam ID} sets fed back by the JAB node may be limited        to up to N. When the number of IAB nodes detected by the JAB        node is greater than N, the JAB node may feed back information        about N LAB nodes having the best N detection performance (e.g.,        received power, RSRP, or the like).

After performing JAB measurement using discovery signal B, the IAB nodemay feed back the measurement result to the parent node or the DgNB. Thefeedback may be transmitted via a PUCCH and/or a PUSCH. Feedbackinformation may include the following details.

-   -   Measurement result per JAB node ID and beam ID: The JAB node may        measure each JAB node or {JAB node ID, beam ID} set and may        transmit feedback thereon. Here, RSRP, RSRQ, and/or a received        signal strength indicator (RSSI) may be measured.

As in [Method A] for the method for transmitting and receiving thediscovery signal, when discovery signal A and discovery signal B aredefined as one discovery signal, the IAB node may include informationabout a detected JAB node ID and a beam ID and information about ameasurement result per IAB node and beam ID together.

Hereinafter, a discovery signal transmission scenario will be described.

Specifically, proposed below are a scenario in which JAB nodes transmita discovery signal and perform detection and measurement using thediscovery signal and a method for transmitting and receiving a discoverysignal in the scenario.

First, the types of neighboring nodes are defined from the perspectiveof one node.

-   -   Detected node: After a node establishes a connection to a        specific node, the node may discover near nodes by performing a        detection process. Nodes detected using a detection signal may        be referred to as neighboring nodes.    -   Measurement node: Among detected nodes, nodes determined to have        a good channel condition and thus selected to be subjected to        continuous measurement may be referred to as measurement nodes.        In particular, all detected nodes may be measurement nodes. A        node may select a measurement node from among the detected nodes        on the basis of a specified criterion and may report the        measurement node to a parent node. Alternatively, the node may        report the detected nodes to the parent node, and the parent        node may set a measurement node to be measured. The node may        periodically or aperiodically measure measurement nodes thereof        and may report the measurement result to the parent node.    -   Parent node: A node may select a node to be a new parent node        among measurement nodes thereof and may establish a connection        therewith. In some cases, the node may select a node to be a new        parent node directly from among detected nodes and may establish        a connection therewith.

First, a scenario in which a node discovers a new node in the presenceof a connected parent node may be illustrated below.

-   -   When a new node occurs: When a new node occurs and thus the node        establishes a connection with a different node through an        initial access process, the node also needs to detect        neighboring nodes, and existing nodes need to detect the new        node. This detection process is performed when a new node        occurs, and is thus rarely performed. Therefore, detection may        be aperiodically performed. When a new node occurs and a        connection is established, this information may be reported to a        DgNB. Then, the DgNB may trigger nodes to transmit a discovery        signal and to perform detection.    -   When a node to be measured is changed: When the channel quality        of nodes that the node measures is poor due to a change in        channel environment, it is necessary to configure new        measurement nodes. In this case, a measurement node may be newly        configured or changed by performing new detection. When a        detection process is performed aperiodically, if the node        determines that it is necessary to change measurement nodes        thereof, the node or the parent node thereof may transmit a        request that a detection process is necessary to the DgNB. Upon        receiving the request, the DgNB may trigger nodes to transmit a        discovery signal and to perform detection. In this case,        characteristically, 1) nodes receiving a triggering message may        perform both transmission of a detection signal and detection.        Alternatively, in this case, characteristically, 2) transmission        of a detection signal and detection may be separately set        through a triggering message. Here, a node set to perform only        detection may perform only detection without transmitting a        detection signal, and a node set to perform only transmission of        a detection signal may only transmit a detection signal without        detecting other nodes. Further, when both transmission of a        detection signal and detection are set, a node may perform both        transmission of a detection signal and detection. With this        method, a node that needs to change measurement nodes and thus        transmits a detection request to the DgNB may perform only        detection, while other nodes that do not need to change        measurement nodes may only transmit a detection signal.

When a detection process is periodically performed, a node mayperiodically perform a detection process to change a measurement nodeset thereof

-   -   When there is a mobile node or when a node is a wireless node:        When a neighboring node is a wireless node or when a node is a        wireless node, a node continuously existing nearby may be        changed. In this case, a measurement node may be newly        configured or changed by periodically performing detection.        Therefore, a detection procedure may be performed periodically        for this case. Alternatively, the DgNB may set whether to        perform detection aperiodically or periodically through system        information or RRC.

Next, an operation in a situation where a node disconnected from aparent node discovers a new node in order to connect to a new parentnode may be illustrated below.

-   -   In this case, the node may perform a new initial access        procedure to search for a new parent node and to establish a        connection to the new parent node.    -   When there is a measurement node that the node measures before        disconnected from the previous parent node, the node may select        one of measurement nodes and may establish a connection thereto.    -   When periodic detection is set, the node may establish a        connection to a node detected by performing detection at a        detection time.    -   When aperiodic detection is set, if a specific node and a parent        node are disconnected, the parent node detecting the        disconnection may report the disconnection to the DgNB. Then,        the DgNB may trigger neighboring nodes to transmit a detection        signal. This transmission of a detection signal may be performed        once or periodically for a specified time period. The node        disconnected from the parent node may attempt detection,        expecting other nodes to transmit a detection signal. This        detection may be performed aperiodically or periodically through        a predetermined resource.

FIG. 21 is a flowchart illustrating a detection method performed by afirst node according to an embodiment of the disclosure.

Referring to FIG. 21, the first node receives detection configurationinformation from a second node (S2110).

When receiving detection request information from the second node, thefirst node transmits a detection signal to a neighboring node on thebasis of the detection configuration information (S2120). Here, thedetection signal may be transmitted aperiodically. In addition, thedetection signal may be transmitted on the basis of beam sweeping. Thedetection signal may be different from a synchronization signal block(SSB) transmitted by the first node to a UE. Specifically, the detectionsignal may be different from the SSB in at least one of transmissiontiming, a transmission period, and resource allocation.

FIG. 22 schematically shows an example to which the disclosure isapplied.

FIG. 22 illustrates an example in which node 1 detects and/or measuresnode 4 and node 5 when node 1, node 2, and node 3 establish an IABnetwork. Here, node 2 may be a parent node of node 1, and node 3 may bea child node of node 1.

Referring to FIG. 22, node 1 may receive detection configurationinformation from node 2. The detection configuration information mayinclude information about a transmission offset, a transmission beamdirection, and the like for a detection signal transmitted by node 1.

Node 1 may also receive a detection signal transmitted by node 4 and/ornode 5. Here, the reception operation of node 1 may be performed on thebasis of detection signal reception configuration information receivedfrom node 2.

Node 1 may transmit feedback information about a detection result tonode 2, which is the parent node. Here, the feedback information aboutthe detection result may be transmitted aperiodically.

When detecting node 4 and/or node 5, node 1 may transmit a measurementsignal to node 4 and/or node 5. Here, node 1 may also receive ameasurement signal transmitted from node 4 and/or node 5. Further, node1 may perform a measurement operation on the basis of a measurementconfiguration received from node 2. In this case, node 1 may transmitmeasurement feedback information including a measurement result to node2, which is the parent node. Here, the measurement feedback informationmay be transmitted periodically.

Node 1 may measure node 4 and/or node 5 and determine whether to link tonode 4 and/or node 5 on the basis of the measurement result. Here, thelink may be such that node 1 changes the parent node thereof or mayconnect the child node thereof. For example, when the results ofdetection and measurement by node 1 show that the state of a connectionwith node 4 or the quality of communication therewith is better thanthat with node 2, node 1 may change the parent node from node 2 to node4.

Although FIG. 22 illustrates only some embodiments of the disclosure,various embodiments proposed in the disclosure may be applied, and aredundant description is will be omitted.

FIG. 23 is a flowchart illustrating a method in which a node perform anaperiodic detection operation and a periodic measurement operationaccording to an embodiment of the disclosure.

Referring to FIG. 23, a parent node transmits an IAB detectionconfiguration and an IAB measurement configuration to a child node(S23010). Here, the IAB detection configuration and the IAB measurementconfiguration may be simultaneously transmitted as shown in FIG. 23, ormay be separately transmitted. A detailed description of the IABdetection configuration and the IAB measurement configuration is thesame as described above, and thus a redundant description is omitted.

The parent node transmits an IAB detection request from the child node(S23020). Here, a detailed description of the IAB detection request isthe same as described above, and thus a redundant description isomitted.

The child node performs transmission of a discovery signal and detectionin response to the IAB detection request (S23030). Here, a detaileddescription of the transmission of the discovery signal and thedetection is the same as described above, and thus a redundantdescription is omitted.

The child node transmits an IAB detection report to the parent node(S23040). Here, the IAB detection report may be IAB detection feedback,and the IAB detection report may be performed aperiodically. A detaileddescription of the IAB detection report is the same as described above,and thus a redundant description is be omitted.

The parent node transmits an IAB measurement configuration to the childnode (S23050). This step may be an additional step, a detaileddescription of which is the same as described above, and thus aredundant description is be omitted.

The child node performs transmission of a discovery signal andmeasurement and transmits an IAB measurement report to the parent node(S23060 and S23061 to S23100 and S23101). Here, the transmission of thediscovery signal and the measurement may be performed periodically witha specific period. The IAB measurement report may also be transmittedperiodically. A detailed description of the transmission of thediscovery signal and the measurement is the same as described above, andthus a redundant description is omitted.

FIG. 24 is a flowchart illustrating a method in which a node perform aperiodic detection operation and a periodic measurement operationaccording to an embodiment of the disclosure.

Referring to FIG. 24, a parent node transmits an IAB detectionconfiguration and an IAB measurement configuration to a child node(S24010). A detailed description of the IAB detection configuration andthe IAB measurement configuration is the same as described above, andthus a redundant description is omitted.

The child node performs transmission of a discovery signal and detection(S24020) and transmits an IAB detection report to the parent node(S24030). Here, the IAB detection report may be IAB detection feedback.Here, a detailed description of the transmission of the discoverysignal, the detection, and the IAB detection report is the same asdescribed above, and thus a redundant description is omitted.

The parent node transmits an IAB measurement configuration to the childnode (S24040). This step may be an additional step, a detaileddescription of which is the same as described above, and thus aredundant description is be omitted.

The child node performs transmission of a discovery signal andmeasurement and transmits an IAB measurement report to the parent node(S24050 and S24051 to S24070 and S24071). Here, the transmission of thediscovery signal, the measurement, and the IAB measurement report may beperformed periodically with a specific period. A detailed description ofeach operation is the same as described above, and thus a redundantdescription is omitted.

The child node performs transmission of a discovery signal and detection(S24080) and transmits an IAB detection report to the parent node(S24090). Here, in FIG. 24, the duration of steps 24020 and S24030 andthe duration of the steps 24080 and S24090 may be the same. That is, thetransmission of the discovery signal, the detection, and the IABdetection report operation may be performed periodically with a specificperiod. Here, a detailed description of the transmission of thediscovery signal, the detection, and the IAB detection report is thesame as described above, and thus a redundant description is omitted.

The parent node transmits an IAB measurement configuration to the childnode (S24100). This step may be an additional step, a detaileddescription of which is the same as described above, and thus aredundant description is be omitted.

The child node performs transmission of a discovery signal andmeasurement and transmits an IAB measurement report to the parent node(S24110 and S24111 to S24120 and S24121). Here, the transmission of thediscovery signal, the measurement, and the IAB measurement report may beperformed periodically with a specific period. A detailed description ofeach operation is the same as described above, and thus a redundantdescription is omitted.

From the viewpoint of a reception node receiving a detection signal anda measurement signal, when the detection signal is aperiodicallytransmitted, a detection operation using the detection signal may alsobe aperiodically performed. In addition, when transmitting detectionfeedback information, which is information including a detection result,to a parent node thereof, the reception node may aperiodically transmitthe detection feedback information to the parent node.

When the measurement signal is periodically transmitted, a measurementoperation using the measurement signal may also be periodicallyperformed. In addition, when transmitting measurement feedbackinformation, which is information including a measurement result, to theparent node, the reception node may periodically transmit themeasurement feedback information to the parent node.

Further, regardless of the periodicity of the detection signal and themeasurement signal, the detection feedback information may betransmitted aperiodically, and the measurement feedback information maybe transmitted periodically.

Hereinafter, a device to which the disclosure is applicable will bedescribed.

FIG. 25 illustrates a wireless communication device according to anembodiment of the disclosure.

Referring to FIG. 25, a wireless communication system may include afirst device 9010 and a second device 9020.

The first device 9010 may be a base station, a network node, atransmission UE, a reception UE, a wireless device, a wirelesscommunication device, a vehicle, a vehicle having an autonomous drivingfunction, a connected car, a unmanned aerial vehicle (UAV), anartificial intelligence (AI) module, a robot, an augmented reality (AR)device, a virtual reality (VR) device, a mixed reality (MR) device, ahologram device, a public safety device, an MTC device, an IoT device, amedical device, a financial technology (fintech) device (financialdevice), a security device, a climate/environment device, a devicerelated to a 5G service, or a device related to the fourth industrialrevolution.

The second device 9020 may be a base station, a network node, atransmission UE, a reception UE, a wireless device, a wirelesscommunication device, a vehicle, a vehicle having an autonomous drivingfunction, a connected car, a UAV, an AI module, a robot, an AR device, aVR device, an MR device, a hologram device, a public safety device, anMTC device, an IoT device, a medical device, a fintech device (financialdevice), a security device, a climate/environment device, a devicerelated to a 5G service, or a device related to the fourth industrialrevolution.

For example, a UE may be a mobile phone, a smartphone, a laptopcomputer, a digital broadcasting UE, a personal digital assistant (PDA),a portable multimedia player (PMP), a navigation device, a slate PC, atablet PC, an ultrabook, a wearable device (e.g., a smartwatch, smartglasses, and a head-mounted display (HMD)). For example, the HMD may bea display device worn on the head. For example, an HMD may be used toimplement VR, AR, or MR.

For example, a UAV may be an aircraft without a human pilot on board,the flight of which operates by a radio control signal. For example, theVR device may include a device for realizing an object or a backgroundin a virtual world. For example, the AR device may include a device forconnecting an object or a background in a virtual world to an object ora background in the real world. For example, the MR device may include adevice for combining an object or a background in a virtual world withan object or a background in the real world. For example, the hologramdevice may include a device for realizing a 360-degree stereoscopicimage by recording and reproducing stereoscopic information usingholography, which is interference of light resulting from two laserbeams encountering each other. For example, the public safety device mayinclude an image relay device or an imaging device that can be worn on auser's body. For example, the MTC device and the IoT device may bedevices that do not require direct human intervention or manipulation.For example, the MTC device and the IoT device may include a smartmeter, a vending machine, a thermometer, a smart bulb, a door lock orvarious sensors. For example, the medical device may be a device usedfor diagnosing, treating, alleviating, curing, or preventing a disease.For example, the medical device may be a device used for diagnosing,treating, alleviating, or correcting an injury or a disorder. Forexample, a medical device may be a device used for inspecting,replacing, or modifying a structure or a function. For example, themedical device may be a device used for controlling pregnancy. Forexample, the medical device may include a medical device, a surgicaldevice, a (in vitro) diagnostic device, a hearing aid, or a treatmentdevice. For example, the security device may be a device installed toprevent a risk that may occur and to maintain safety. For example, thesecurity device may be a camera, a CCTV, a recorder, or a black box. Forexample, the fintech device may be a device capable of providing afinancial service, such as mobile payment. For example, the fintechdevice may include a payment device or a point-of-sale (POS) device. Forexample, the climate/environment device may include a device formonitoring or predicting a climate/environment.

The first device 9010 may include at least one processor, such as aprocessor 9011, at least one memory, such as a memory 9012, and at leastone transceiver, such as a transceiver 9013. The processor 9011 mayperform the foregoing functions, procedures, and/or methods. Theprocessor 9011 may perform one or more protocols. For example, theprocessor 9011 may implement one or more layers of radio interfaceprotocols. The memory 9012 may be connected to the processor 9011 andmay store various types of information and/or commands. The transceiver9013 may be connected to the processor 9011 and may be controlled totransmit and receive a radio signal.

The second device 9020 may include at least one processor, such as aprocessor 9021, at least one memory, such as a memory 9022, and at leastone transceiver, such as a transceiver 9023. The processor 9021 mayperform the foregoing functions, procedures, and/or methods. Theprocessor 9021 may perform one or more protocols. For example, theprocessor 9021 may implement one or more layers of radio interfaceprotocols. The memory 9022 may be connected to the processor 9021 andmay store various types of information and/or commands. The transceiver9023 may be connected to the processor 9021 and may be controlled totransmit and receive a radio signal.

The memory 9012 and/or the memory 9022 may be connected inside oroutside the processor 9011 and/or the processor 9021, respectively, andmay also be connected to other processors through various techniques,such as a wired or wireless connection.

The first device 9010 and/or the second device 9020 may have one or moreantennas. For example, an antenna 9014 and/or an antenna 9024 may beconfigured to transmit and receive a radio signal.

FIG. 26 is a block diagram showing components of a transmitting device1810 and a receiving device 1820 for implementing the presentdisclosure. Here, the transmitting device and the receiving device maybe a base station and a terminal.

The transmitting device 1810 and the receiving device 1820 mayrespectively include transceivers 1812 and 1822 capable of transmittingor receiving radio frequency (RF) signals carrying information, data,signals and messages, memories 1813 and 1823 for storing various typesof information regarding communication in a wireless communicationsystem, and processors 1811 and 1821 connected to components such as thetransceivers 1812 and 1822 and the memories 1813 and 1823 and configuredto control the memories 1813 and 1823 and/or the transceivers 1812 and1822 such that the corresponding devices perform at least one ofembodiments of the present disclosure.

The memories 1813 and 1823 can store programs for processing and controlof the processors 1811 and 1821 and temporarily store input/outputinformation. The memories 1813 and 1823 may be used as buffers.

The processors 1811 and 1821 generally control overall operations ofvarious modules in the transmitting device and the receiving device.Particularly, the processors 1811 and 1821 can execute various controlfunctions for implementing the present disclosure. The processors 1811and 1821 may be referred to as controllers, microcontrollers,microprocessors, microcomputers, etc. The processors 1811 and 1821 canbe realized by hardware, firmware, software or a combination thereof.When the present disclosure is realized using hardware, the processors1811 and 1821 may include ASICs (application specific integratedcircuits), DSPs (digital signal processors), DSPDs (digital signalprocessing devices), PLDs (programmable logic devices), FPGAs (fieldprogrammable gate arrays) or the like configured to implement thepresent disclosure. When the present disclosure is realized usingfirmware or software, the firmware or software may be configured toinclude modules, procedures or functions for performing functions oroperations of the present disclosure, and the firmware or softwareconfigured to implement the present disclosure may be included in theprocessors 1811 and 1821 or stored in the memories 1813 and 1823 andexecuted by the processors 1811 and 1821.

The processor 1811 of the transmitting device 1810 can performpredetermined coding and modulation on a signal and/or data to betransmitted to the outside and then transmit the signal and/or data tothe transceiver 1812. For example, the processor 1811 can performdemultiplexing, channel coding, scrambling and modulation on a datastring to be transmitted to generate a codeword. The codeword caninclude information equivalent to a transport block which is a datablock provided by an MAC layer. One transport block (TB) can be codedinto one codeword. Each codeword can be transmitted to the receivingdevice through one or more layers. The transceiver 1812 may include anoscillator for frequency up-conversion. The transceiver 1812 may includeone or multiple transmission antennas.

The signal processing procedure of the receiving device 1820 may bereverse to the signal processing procedure of the transmitting device1810. The transceiver 1822 of the receiving device 1820 can receive RFsignals transmitted from the transmitting device 1810 under the controlof the processor 1821. The transceiver 1822 may include one or multiplereception antennas. The transceiver 1822 can frequency-down-convertsignals received through the reception antennas to restore basebandsignals. The transceiver 1822 may include an oscillator for frequencydown conversion. The processor 1821 can perform decoding anddemodulation on RF signals received through the reception antennas torestore data that is intended to be transmitted by the transmittingdevice 1810.

The transceivers 1812 and 1822 may include one or multiple antennas. Theantennas can transmit signals processed by the transceivers 1812 and1822 to the outside or receive RF signals from the outside and deliverthe RF signal to the transceivers 1812 and 1822 under the control of theprocessors 1811 and 1821 according to an embodiment of the presentdisclosure. The antennas may be referred to as antenna ports. Eachantenna may correspond to one physical antenna or may be configured by acombination of a plurality of physical antenna elements. A signaltransmitted from each antenna cannot be decomposed by the receivingdevice 1820. A reference signal (RS) transmitted corresponding to anantenna defines an antenna from the viewpoint of the receiving device1820 and can allow the receiving device 1820 to be able to estimate achannel with respect to the antenna irrespective of whether the channelis a single radio channel from a physical antenna or a composite channelfrom a plurality of physical antenna elements including the antenna.That is, an antenna can be defined such that a channel carrying a symbolon the antenna can be derived from the channel over which another symbolon the same antenna is transmitted. A transceiver which supports amulti-input multi-output (MIMO) function of transmitting and receivingdata using a plurality of antennas may be connected to two or moreantennas.

FIG. 27 illustrates an example of a signal processing module structurein the transmitting device 1810. Here, signal processing can beperformed by a processor of a base station/terminal, such as theprocessors 1811 and 1821 of FIG. 26.

Referring to FIG. 27, the transmitting device 1810 included in aterminal or a base station may include scramblers 301, modulators 302, alayer mapper 303, an antenna port mapper 304, resource block mappers 305and signal generators 306.

The transmitting device 1810 can transmit one or more codewords. Codedbits in each codeword are scrambled by the corresponding scrambler 301and transmitted over a physical channel. A codeword may be referred toas a data string and may be equivalent to a transport block which is adata block provided by the MAC layer.

Scrambled bits are modulated into complex-valued modulation symbols bythe corresponding modulator 302. The modulator 302 can modulate thescrambled bits according to a modulation scheme to arrangecomplex-valued modulation symbols representing positions on a signalconstellation. The modulation scheme is not limited and m-PSK (m-PhaseShift Keying) or m-QAM (m-Quadrature Amplitude Modulation) may be usedto modulate the coded data. The modulator may be referred to as amodulation mapper.

The complex-valued modulation symbols can be mapped to one or moretransport layers by the layer mapper 303. Complex-valued modulationsymbols on each layer can be mapped by the antenna port mapper 304 fortransmission on an antenna port.

Each resource block mapper 305 can map complex-valued modulation symbolswith respect to each antenna port to appropriate resource elements in avirtual resource block allocated for transmission. The resource blockmapper can map the virtual resource block to a physical resource blockaccording to an appropriate mapping scheme. The resource block mapper305 can allocate complex-valued modulation symbols with respect to eachantenna port to appropriate subcarriers and multiplex the complex-valuedmodulation symbols according to a user.

Each signal generator 306 can modulate complex-valued modulation symbolswith respect to each antenna port, that is, antenna-specific symbols,according to a specific modulation scheme, for example, OFDM (OrthogonalFrequency Division Multiplexing), to generate a complex-valued timedomain OFDM symbol signal. The signal generator can perform IFFT(Inverse Fast Fourier Transform) on the antenna-specific symbols, and aCP (cyclic Prefix) can be inserted into time domain symbols on whichIFFT has been performed. OFDM symbols are subjected to digital-analogconversion and frequency up-conversion and then transmitted to thereceiving device through each transmission antenna. The signal generatormay include an IFFT module, a CP inserting unit, a digital-to-analogconverter (DAC) and a frequency upconverter.

FIG. 28 illustrates another example of the signal processing modulestructure in the transmitting device 1810. Here, signal processing canbe performed by a processor of a terminal/base station, such as theprocessors 1811 and 1821 of FIG. 26.

Referring to FIG. 28, the transmitting device 1810 included in aterminal or a base station may include scramblers 401, modulators 402, alayer mapper 403, a precoder 404, resource block mappers 405 and signalgenerators 406.

The transmitting device 1810 can scramble coded bits in a codeword bythe corresponding scrambler 401 and then transmit the scrambled codedbits through a physical channel.

Scrambled bits are modulated into complex-valued modulation symbols bythe corresponding modulator 402. The modulator can modulate thescrambled bits according to a predetermined modulation scheme to arrangecomplex-valued modulation symbols representing positions on a signalconstellation. The modulation scheme is not limited and pi/2-BPSK(pi/2-Binary Phase Shift Keying), m-PSK (m-Phase Shift Keying) or m-QAM(m-Quadrature Amplitude Modulation) may be used to modulate the codeddata.

The complex-valued modulation symbols can be mapped to one or moretransport layers by the layer mapper 403.

Complex-valued modulation symbols on each layer can be precoded by theprecoder 404 for transmission on an antenna port. Here, the precoder mayperform transform precoding on the complex-valued modulation symbols andthen perform precoding. Alternatively, the precoder may performprecoding without performing transform precoding. The precoder 404 canprocess the complex-valued modulation symbols according to MIMO usingmultiple transmission antennas to output antenna-specific symbols anddistribute the antenna-specific symbols to the corresponding resourceblock mapper 405. An output z of the precoder 404 can be obtained bymultiplying an output y of the layer mapper 403 by an N*M precodingmatrix W. Here, N is the number of antenna ports and M is the number oflayers.

Each resource block mapper 405 maps complex-valued modulation symbolswith respect to each antenna port to appropriate resource elements in avirtual resource block allocated for transmission.

The resource block mapper 405 can allocate complex-valued modulationsymbols to appropriate subcarriers and multiplex the complex-valuedmodulation symbols according to a user.

Each signal generator 406 can modulate complex-valued modulation symbolsaccording to a specific modulation scheme, for example, OFDM, togenerate a complex-valued time domain OFDM symbol signal. The signalgenerator 406 can perform IFFT (Inverse Fast Fourier Transform) onantenna-specific symbols, and a CP (cyclic Prefix) can be inserted intotime domain symbols on which IFFT has been performed. OFDM symbols aresubjected to digital-analog conversion and frequency up-conversion andthen transmitted to the receiving device through each transmissionantenna. The signal generator 406 may include an IFFT module, a CPinserting unit, a digital-to-analog converter (DAC) and a frequencyupconverter.

The signal processing procedure of the receiving device 1820 may bereverse to the signal processing procedure of the transmitting device.Specifically, the processor 1821 of the transmitting device 1810 decodesand demodulates RF signals received through antenna ports of thetransceiver 1822. The receiving device 1820 may include a plurality ofreception antennas, and signals received through the reception antennasare restored to baseband signals, and then multiplexed and demodulatedaccording to MIMO to be restored to a data string intended to betransmitted by the transmitting device 1810. The receiving device 1820may include a signal restoration unit for restoring received signals tobaseband signals, a multiplexer for combining and multiplexing receivedsignals, and a channel demodulator for demodulating multiplexed signalstrings into corresponding codewords. The signal restoration unit, themultiplexer and the channel demodulator may be configured as anintegrated module or independent modules for executing functionsthereof. More specifically, the signal restoration unit may include ananalog-to-digital converter (ADC) for converting an analog signal into adigital signal, a CP removal unit for removing a CP from the digitalsignal, an FET module for applying FFT (fast Fourier transform) to thesignal from which the CP has been removed to output frequency domainsymbols, and a resource element demapper/equalizer for restoring thefrequency domain symbols to antenna-specific symbols. Theantenna-specific symbols are restored to transport layers by themultiplexer and the transport layers are restored by the channeldemodulator to codewords intended to be transmitted by the transmittingdevice.

FIG. 29 illustrates an example of a wireless communication deviceaccording to an implementation example of the present disclosure.

Referring to FIG. 29, the wireless communication device, for example, aterminal may include at least one of a processor 2310 such as a digitalsignal processor (DSP) or a microprocessor, a transceiver 2335, a powermanagement module 2305, an antenna 2340, a battery 2355, a display 2315,a keypad 2320, a global positioning system (GPS) chip 2360, a sensor2365, a memory 2330, a subscriber identification module (SIM) card 2325,a speaker 2345 and a microphone 2350. A plurality of antennas and aplurality of processors may be provided.

The processor 2310 can implement functions, procedures and methodsdescribed in the present description. The processor 2310 in FIG. 29 maybe the processors 1811 and 1821 in FIG. 26.

The memory 2330 is connected to the processor 2310 and storesinformation related to operations of the processor. The memory may belocated inside or outside the processor and connected to the processorthrough various techniques such as wired connection and wirelessconnection. The memory 2330 in FIG. 29 may be the memories 1813 and 1823in FIG. 26.

A user can input various types of information such as telephone numbersusing various techniques such as pressing buttons of the keypad 2320 oractivating sound using the microphone 2350. The processor 2310 canreceive and process user information and execute an appropriate functionsuch as calling using an input telephone number. In some scenarios, datacan be retrieved from the SIM card 2325 or the memory 2330 to executeappropriate functions. In some scenarios, the processor 2310 can displayvarious types of information and data on the display 2315 for userconvenience.

The transceiver 2335 is connected to the processor 2310 and transmitand/or receive RF signals. The processor can control the transceiver inorder to start communication or to transmit RF signals including varioustypes of information or data such as voice communication data. Thetransceiver includes a transmitter and a receiver for transmitting andreceiving RF signals. The antenna 2340 can facilitate transmission andreception of RF signals. In some implementation examples, when thetransceiver receives an RF signal, the transceiver can forward andconvert the signal into a baseband frequency for processing performed bythe processor. The signal can be processed through various techniquessuch as converting into audible or readable information to be outputthrough the speaker 2345. The transceiver in FIG. 29 may be thetransceivers 1812 and 1822 in FIG. 26.

Although not shown in FIG. 29, various components such as a camera and auniversal serial bus (USB) port may be additionally included in theterminal. For example, the camera may be connected to the processor2310.

FIG. 29 is an example of implementation with respect to the terminal andimplementation examples of the present disclosure are not limitedthereto. The terminal need not essentially include all the componentsshown in FIG. 29. That is, some of the components, for example, thekeypad 2320, the GPS chip 2360, the sensor 2365 and the SIM card 2325may not be essential components. In this case, they may not be includedin the terminal.

FIG. 30 shows examples of 5G usage scenarios to which the technicalfeatures of the present disclosure can be applied. The 5G usagescenarios shown in FIG. 30 are only exemplary, and the technicalfeatures of the present disclosure can be applied to other 5G usagescenarios which are not shown in FIG. 30.

Referring to FIG. 30, the three main requirements areas of 5G include(1) enhanced mobile broadband (eMBB) domain, (2) massive machine typecommunication (mMTC) area, and (3) ultra-reliable and low latencycommunications (URLLC) area. Some use cases may require multiple areasfor optimization and, other use cases may only focus on only one keyperformance indicator (KPI). 5G is to support these various use cases ina flexible and reliable way.

eMBB focuses on across-the-board enhancements to the data rate, latency,user density, capacity and coverage of mobile broadband access. The eMBBaims ˜10 Gbps of throughput. eMBB far surpasses basic mobile Internetaccess and covers rich interactive work and media and entertainmentapplications in cloud and/or augmented reality. Data is one of the keydrivers of 5G and may not be able to see dedicated voice services forthe first time in the 5G era. In 5G, the voice is expected to beprocessed as an application simply using the data connection provided bythe communication system. The main reason for the increased volume oftraffic is an increase in the size of the content and an increase in thenumber of applications requiring high data rates. Streaming services(audio and video), interactive video and mobile Internet connectivitywill become more common as more devices connect to the Internet. Many ofthese applications require always-on connectivity to push real-timeinformation and notifications to the user. Cloud storage andapplications are growing rapidly in mobile communication platforms,which can be applied to both work and entertainment. Cloud storage is aspecial use case that drives growth of uplink data rate. 5G is also usedfor remote tasks on the cloud and requires much lower end-to-end delayto maintain a good user experience when the tactile interface is used.In entertainment, for example, cloud games and video streaming areanother key factor that increases the demand for mobile broadbandcapabilities. Entertainment is essential in smartphones and tabletsanywhere, including high mobility environments such as trains, cars andairplanes. Another use case is augmented reality and informationretrieval for entertainment. Here, augmented reality requires very lowlatency and instantaneous data amount.

mMTC is designed to enable communication between devices that arelow-cost, massive in number and battery-driven, intended to supportapplications such as smart metering, logistics, and field and bodysensors. mMTC aims ˜10 years on battery and/or ˜1 million devices/km².mMTC allows seamless integration of embedded sensors in all areas and isone of the most widely used 5G applications. Potentially by 2020, IoTdevices are expected to reach 20.4 billion. Industrial IoT is one of theareas where 5G plays a key role in enabling smart cities, assettracking, smart utilities, agriculture and security infrastructures.

URLLC will make it possible for devices and machines to communicate withultra-reliability, very low latency and high availability, making itideal for vehicular communication, industrial control, factoryautomation, remote surgery, smart grids and public safety applications.URLLC aims ˜1 ms of latency. URLLC includes new services that willchange the industry through links with ultra-reliability/low latency,such as remote control of key infrastructure and self-driving vehicles.The level of reliability and latency is essential for smart gridcontrol, industrial automation, robotics, drones control andcoordination.

Next, a plurality of use cases included in the triangle of FIG. 30 willbe described in more detail.

5G can complement fiber-to-the-home (FTTH) and cable-based broadband (orDOCSIS) as a means of delivering streams rated from hundreds of megabitsper second to gigabits per second. This high speed can be required todeliver TVs with resolutions of 4K or more (6K, 8K and above) as well asvirtual reality (VR) and augmented reality (AR). VR and AR applicationsinclude mostly immersive sporting events. Certain applications mayrequire special network settings. For example, in the case of a VR game,a game company may need to integrate a core server with an edge networkserver of a network operator to minimize delay.

Automotive is expected to become an important new driver for 5G, withmany use cases for mobile communications to vehicles. For example,entertainment for passengers demands high capacity and high mobilebroadband at the same time. This is because future users will continueto expect high-quality connections regardless of their location andspeed. Another use case in the automotive sector is an augmented realitydashboard. The driver can identify an object in the dark on top of whatis being viewed through the front window through the augmented realitydashboard. The augmented reality dashboard displays information thatwill inform the driver about the object's distance and movement. In thefuture, the wireless module enables communication between vehicles,information exchange between the vehicle and the supportinginfrastructure, and information exchange between the vehicle and otherconnected devices (e.g. devices accompanied by a pedestrian). The safetysystem allows the driver to guide the alternative course of action sothat he can drive more safely, thereby reducing the risk of accidents.The next step will be a remotely controlled vehicle or self-drivingvehicle. This requires a very reliable and very fast communicationbetween different self-driving vehicles and between vehicles andinfrastructure. In the future, a self-driving vehicle will perform alldriving activities, and the driver will focus only on traffic that thevehicle itself cannot identify. The technical requirements ofself-driving vehicles require ultra-low latency and high-speedreliability to increase traffic safety to a level not achievable byhumans.

Smart cities and smart homes, which are referred to as smart societies,will be embedded in high density wireless sensor networks. Thedistributed network of intelligent sensors will identify conditions forcost and energy-efficient maintenance of a city or house. A similarsetting can be performed for each home. Temperature sensors, windows andheating controllers, burglar alarms and appliances are all wirelesslyconnected. Many of these sensors typically require low data rate, lowpower and low cost. However, for example, real-time HD video may berequired for certain types of devices for monitoring.

The consumption and distribution of energy, including heat or gas, ishighly dispersed, requiring automated control of distributed sensornetworks. The smart grid interconnects these sensors using digitalinformation and communication technologies to collect and act oninformation. This information can include supplier and consumerbehavior, allowing the smart grid to improve the distribution of fuel,such as electricity, in terms of efficiency, reliability, economy,production sustainability, and automated methods. The smart grid can beviewed as another sensor network with low latency.

The health sector has many applications that can benefit from mobilecommunications. Communication systems can support telemedicine toprovide clinical care in remote locations. This can help to reducebarriers to distance and improve access to health services that are notcontinuously available in distant rural areas. It is also used to savelives in critical care and emergency situations. Mobile communicationbased wireless sensor networks can provide remote monitoring and sensorsfor parameters such as heart rate and blood pressure.

Wireless and mobile communications are becoming increasingly importantin industrial applications. Wiring costs are high for installation andmaintenance. Thus, the possibility of replacing a cable with a wirelesslink that can be reconfigured is an attractive opportunity in manyindustries. However, achieving this requires that wireless connectionsoperate with similar delay, reliability, and capacity as cables and thattheir management is simplified. Low latency and very low errorprobabilities are new requirements that need to be connected to 5G.

Logistics and freight tracking are important use cases of mobilecommunications that enable tracking of inventory and packages anywhereusing location based information systems. Use cases of logistics andfreight tracking typically require low data rates, but require a largerange and reliable location information.

Hereinafter, technical fields to which the present disclosure can beapplied fusionally will be described.

<Artificial Intelligence: AI>

AI refers to artificial intelligence and/or the field of studyingmethodology for making it. Machine learning is a field of studyingmethodologies that define and solve various problems dealt with in AI.Machine learning may be defined as an algorithm that enhances theperformance of a task through a steady experience with any task.

An artificial neural network (ANN) is a model used in machine learning.It can mean a whole model of problem-solving ability, consisting ofartificial neurons (nodes) that form a network of synapses. An ANN canbe defined by a connection pattern between neurons in different layers,a learning process for updating model parameters, and/or an activationfunction for generating an output value.

An ANN may include an input layer, an output layer, and optionally oneor more hidden layers. Each layer may contain one or more neurons, andan ANN may include a synapse that links neurons to neurons. In an ANN,each neuron can output a summation of the activation function for inputsignals, weights, and deflections input through the synapse.

Model parameters are parameters determined through learning, includingdeflection of neurons and/or weights of synaptic connections. Thehyper-parameter means a parameter to be set in the machine learningalgorithm before learning, and includes a learning rate, a repetitionnumber, a mini batch size, an initialization function, etc.

The objective of the ANN learning can be seen as determining the modelparameters that minimize the loss function. The loss function can beused as an index to determine optimal model parameters in learningprocess of ANN.

Machine learning can be divided into supervised learning, unsupervisedlearning, and reinforcement learning, depending on the learning method.

Supervised learning is a method of learning ANN with labels given tolearning data. Labels are the answers (or result values) that ANN mustinfer when learning data is input to ANN. Unsupervised learning can meana method of learning ANN without labels given to learning data.Reinforcement learning can mean a learning method in which an agentdefined in an environment learns to select a behavior and/or sequence ofactions that maximizes cumulative compensation in each state.

Machine learning, which is implemented as a deep neural network (DNN)that includes multiple hidden layers among ANN, is also called deeplearning. Deep learning is part of machine learning. In the following,machine learning is used to mean deep learning.

<Robot>

A robot can mean a machine that automatically processes or operates agiven task by its own abilities. In particular, a robot having afunction of recognizing the environment and performingself-determination and operation can be referred to as an intelligentrobot.

Robots can be classified into industrial, medical, household, military,etc., depending on the purpose and field of use.

The robot may include a driving unit including an actuator and/or amotor to perform various physical operations such as moving a robotjoint. In addition, the movable robot may include a wheel, a break, apropeller, etc., in a driving unit, and can travel on the ground or flyin the air through the driving unit.

<Autonomous-Driving/Self-Driving>

The autonomous-driving refers to a technique of self-driving, and anautonomous vehicle refers to a vehicle that travels without a user'soperation or with a minimum operation of a user.

For example, autonomous-driving may include techniques for maintaining alane while driving, techniques for automatically controlling speed suchas adaptive cruise control, techniques for automatically traveling alonga predetermined route, and techniques for traveling by setting a routeautomatically when a destination is set.

The autonomous vehicle may include a vehicle having only an internalcombustion engine, a hybrid vehicle having an internal combustion engineand an electric motor together, and an electric vehicle having only anelectric motor, and may include not only an automobile but also a train,a motorcycle, etc.

Herein, the autonomous vehicle can be regarded as a robot having anautonomous driving function.

<eXtended Reality: XR>

XR are collectively referred to as VR, AR, and MR. VR technologyprovides real-world objects and/or backgrounds only as computer graphic(CG) images, AR technology provides CG images that is virtually createdon real object images, and MR technology is a computer graphicstechnology that mixes and combines virtual objects in the real world.

MR technology is similar to AR technology in that it shows real andvirtual objects together. However, in the AR technology, the virtualobject is used as a complement to the real object, whereas in the MRtechnology, the virtual object and the real object are used in an equalmanner.

XR technology can be applied to HMD, head-up display (HUD), mobilephone, tablet PC, laptop, desktop, TV, digital signage. A device towhich the XR technology is applied may be referred to as an XR device.

FIG. 31 shows an example of an AI device 31100 to which the technicalfeatures of the present disclosure can be applied.

The AI device 31100 may be implemented as a stationary device or amobile device, such as a TV, a projector, a mobile phone, a smartphone,a desktop computer, a notebook, a digital broadcasting terminal, a PDA,a PMP, a navigation device, a tablet PC, a wearable device, a set-topbox (STB), a digital multimedia broadcasting (DMB) receiver, a radio, awashing machine, a refrigerator, a digital signage, a robot, a vehicle,etc.

Referring to FIG. 31, the AI device 31100 may include a communicationpart 31110, an input part 31120, a learning processor 31130, a sensingpart 31140, an output part 31150, a memory 31170, and a processor 31180.

The communication part 31110 can transmit and/or receive data to and/orfrom external devices such as the AI devices and the AI server usingwire and/or wireless communication technology. For example, thecommunication part 31110 can transmit and/or receive sensor information,a user input, a learning model, and a control signal with externaldevices.

The communication technology used by the communication part 31110 mayinclude a global system for mobile communication (GSM), a code divisionmultiple access (CDMA), an LTE/LTE-A, a 5G, a WLAN, a Wi-Fi, Bluetooth®,radio frequency identification (RFID), infrared data association (IrDA),ZigBee, and/or near field communication (NFC).

The input part 31120 can acquire various kinds of data.

Herein, the input part 31120 may include a camera for inputting a videosignal, a microphone for receiving an audio signal, and a user inputpart for receiving information from a user. Herein, a camera and/or amicrophone may be treated as a sensor, and a signal obtained from acamera and/or a microphone may be referred to as sensing data and/orsensor information.

The input part 31120 can acquire input data to be used when acquiring anoutput using learning data and a learning model for model learning. Theinput part 31120 may obtain raw input data, in which case the processor31180 or the learning processor 31130 may extract input features bypreprocessing the input data.

The learning processor 31130 may learn a model composed of an ANN usinglearning data. Herein the learned ANN can be referred to as a learningmodel. The learning model can be used to infer result values for newinput data rather than learning data, and the inferred values can beused as a basis for determining which actions to perform.

Herein, the learning processor 31130 may perform AI processing togetherwith the learning processor 31240 of the AI server 31200.

Herein, the learning processor 31130 may include a memory integratedand/or implemented in the AI device 31100. Alternatively, the learningprocessor 31130 may be implemented using the memory 31170, an externalmemory directly coupled to the AI device 31100, and/or a memorymaintained in an external device.

The sensing part 31140 may acquire at least one of internal informationof the AI device 31100, environment information of the AI device 31100,and/or the user information using various sensors.

Herein, the sensors included in the sensing part 31140 may include aproximity sensor, an illuminance sensor, an acceleration sensor, amagnetic sensor, a gyro sensor, an inertial sensor, an RGB sensor, an IRsensor, a fingerprint recognition sensor, an ultrasonic sensor, anoptical sensor, a microphone, a light detection and ranging (LIDAR),and/or a radar.

The output part 31150 may generate an output related to visual,auditory, tactile, etc.

Herein, the output part 31150 may include a display unit for outputtingvisual information, a speaker for outputting auditory information,and/or a haptic module for outputting tactile information.

The memory 31170 may store data that supports various functions of theAI device 31100. For example, the memory 31170 may store input dataacquired by the input part 31120, learning data, a learning model, alearning history, etc.

The processor 31180 may determine at least one executable operation ofthe AI device 31100 based on information determined and/or generatedusing a data analysis algorithm and/or a machine learning algorithm. Theprocessor 31180 may then control the components of the AI device 31100to perform the determined operation.

Therefore, the processor 31180 may request, retrieve, receive, and/orutilize data in the learning processor 31130 and/or the memory 31170,and may control the components of the AI device 31100 to execute thepredicted operation and/or the operation determined to be desirableamong the at least one executable operation.

Herein, the processor 31180 may generate a control signal forcontrolling the external device, and may transmit the generated controlsignal to the external device, when the external device needs to belinked to perform the determined operation.

The processor 31180 may obtain the intention information for the userinput and determine the user's requirements based on the obtainedintention information.

Herein, the processor 31180 may use at least one of a speech-to-text(STT) engine for converting speech input into a text string and/or anatural language processing (NLP) engine for acquiring intentioninformation of a natural language, to obtain the intention informationcorresponding to the user input.

Herein, at least one of the STT engine and/or the NLP engine may beconfigured as an ANN, at least a part of which is learned according to amachine learning algorithm. At least one of the STT engine and/or theNLP engine may be learned by the learning processor 31130 and/or learnedby the learning processor of the AI server, and/or learned by theirdistributed processing.

The processor 31180 may collect history information including theoperation contents of the AI device 31100 and/or the user's feedback onthe operation, etc. The processor 31180 may store the collected historyinformation in the memory 31170 and/or the learning processor 31130,and/or transmit to an external device such as the AI server. Thecollected history information can be used to update the learning model.

The processor 31180 may control at least some of the components of AIdevice 31100 to drive an application program stored in memory 31170.Furthermore, the processor 31180 may operate two or more of thecomponents included in the AI device 31100 in combination with eachother for driving the application program.

FIG. 32 illustrates an AI server 32200 according to an embodiment of thedisclosure.

Referring to FIG. 32, the AI server 32200 may refer to a device thatlearns an artificial neural network using a machine learning algorithmor uses a learned artificial neural network. Here, the AI server 32200may include a plurality of servers to perform distributed processing andmay be defined as a 5G network. Here, the AI server 32200 may beincluded as a component of an AI device 32100 to perform at least partof AI processing together.

The AI server 32200 may include a communication unit 32210, a memory32230, a learning processor 32240, and a processor 32260.

The communication unit 32210 may transmit and receive data to and froman external device, such as the AI device 32100.

The memory 32230 may include a model storage unit 32231. The modelstorage unit 32231 may store a model (or an artificial neural network32231 a) being learned or having been learned through the learningprocessor 32240.

The learning processor 32240 may train the artificial neural network32231 a using learning data. A learning model may be mounted and used inthe AI server 32200 of the artificial neural network, or may be mountedand used in an external device, such as the AI device 32100.

The learning model may be configured as hardware, software, or acombination of hardware and software. When part or the entirety of thelearning model is configured as software, one or more instructionsincluded in the learning model may be stored in the memory 32230.

The processor 32260 may infer a result value with respect to new inputdata using the learning model and may generate a response or a controlcommand on the basis of the inferred result value.

FIG. 33 shows an example of an AI system 331 to which the technicalfeatures of the present disclosure can be applied.

Referring to FIG. 33, in the AI system 331, at least one of an AI server33200, a robot 33100 a, an autonomous vehicle 33100 b, an XR device33100 c, a smartphone 33100 d and/or a home appliance 33100 e isconnected to a cloud network 33010. The robot 33100 a, the autonomousvehicle 33100 b, the XR device 33100 c, the smartphone 33100 d, and/orthe home appliance 33100 e to which the AI technology is applied may bereferred to as AI devices 33100 a to 33100 e.

The cloud network 33010 may refer to a network that forms part of acloud computing infrastructure and/or resides in a cloud computinginfrastructure. The cloud network 33010 may be configured using a 3Gnetwork, a 4G or LTE network, and/or a 5G network.

That is, each of the devices 33100 a to 33100 e and 33200 consisting theAI system may be connected to each other through the cloud network33010. In particular, each of the devices 33100 a to 33100 e and 33200may communicate with each other through a base station, but may directlycommunicate with each other without using a base station.

The AI server 33200 may include a server for performing AI processingand a server for performing operations on big data.

The AI server 33200 is connected to at least one or more of AI devicesconstituting the AI system 331, i.e. the robot 33100 a, the autonomousvehicle 33100 b, the XR device 33100 c, the smartphone 33100 d and/orthe home appliance 33100 e through the cloud network 33010, and mayassist at least some AI processing of the connected AI devices 33100 ato 33100 e.

The AI server 33200 can learn the ANN according to the machine learningalgorithm on behalf of the AI devices 33100 a to 33100 e, and candirectly store the learning models and/or transmit them to the AIdevices 33100 a to 33100 e.

The AI server 33200 may receive the input data from the AI devices 33100a to 33100 e, infer the result value with respect to the received inputdata using the learning model, generate a response and/or a controlcommand based on the inferred result value, and transmit the generateddata to the AI devices 33100 a to 33100 e.

Alternatively, the AI devices 33100 a to 33100 e may directly infer aresult value for the input data using a learning model, and generate aresponse and/or a control command based on the inferred result value.

Various embodiments of the AI devices 33100 a to 33100 e to which thetechnical features of the present disclosure can be applied will bedescribed. The AI devices 33100 a to 33100 e shown in FIG. 33 can beseen as specific embodiments of the AI device 31100 shown in FIG. 31.

<AI+Robot>

The robot 33100 a may be implemented as a guide robot, a carrying robot,a cleaning robot, a wearable robot, an entertainment robot, a pet robot,an unmanned flying robot, etc., to which AI technology is applied.

The robot 33100 a may include a robot control module for controlling theoperation, and the robot control module may refer to a software moduleand/or a chip implementing the software module.

The robot 33100 a may acquire the state information of the robot 33100 ausing the sensor information acquired from various kinds of sensorsand/or detect (recognize) the surrounding environment and/or the object,and/or generate map data, and/or determine a travel route and/or atravel plan, and/or determine a response to user interaction, and/ordetermine an operation.

The robot 33100 a can use the sensor information acquired from at leastone sensor among the LIDAR, the radar, and/or the camera to determinethe travel route and/or the travel plan.

The robot 33100 a can perform the above-described operations using alearning model composed of at least one ANN. For example, the robot33100 a can recognize the surrounding environment and/or the objectusing the learning model, and can determine the operation using therecognized surrounding information and/or the object information. Thelearning model may be learned directly from the robot 33100 a and/orlearned from an external device such as the AI server 33200.

Herein, the robot 33100 a can directly generate a result using thelearning model and perform an operation. The robot 33100 a may transmitsensor information to an external device such as the AI server 33200 andmay receive the generated result and perform an operation.

The robot 33100 a may determine the travel route and/or the travel planusing at least one of the map data, the object information detected fromthe sensor information and/or the object information acquired from theexternal device, and drive the robot 33100 a according to the determinedtravel route and/or travel plan by controlling the driving unit.

The map data may include object identification information on variousobjects arranged in a space in which the robot 33100 a moves. Forexample, the map data may include object identification information onfixed objects such as walls and doors, and/or on movable objects such aspots and desks. The object identification information may include aname, a type, a distance, and/or a position, etc.

Also, the robot 33100 a can perform the operation and/or run bycontrolling the driving unit based on the control/interaction of theuser. The robot 33100 a may acquire the intention information of theinteraction due to the user's operation and/or voice utterance,determine the response based on the acquired intention information, andperform the operation.

<AI+Autonomous-Driving/Self-Driving>

The autonomous vehicle 33100 b may be implemented as a mobile robot, avehicle, an unmanned aerial vehicle, etc., to which AI technology isapplied.

The autonomous vehicle 33100 b may include an autonomous driving controlmodule for controlling the autonomous driving function, and theautonomous driving control module may refer to a software module and/ora chip implementing the software module. The autonomous driving controlmodule may be included in the autonomous vehicle 33100 b as a componentof the autonomous vehicle 33100 b, but may be connected to the outsideof the autonomous vehicle 1210 b with separate hardware.

The autonomous vehicle 33100 b may acquire the state information of theautonomous vehicle 33100 b using the sensor information acquired fromvarious kinds of sensors and/or detect (recognize) the surroundingenvironment and/or the object, and/or generate map data, and/ordetermine a travel route and/or a travel plan, and/or determine anoperation.

Like the robot 33100 a, the autonomous vehicle 33100 b can use thesensor information acquired from at least one sensor among the LIDAR,the radar, and/or the camera to determine the travel route and/or thetravel plan.

In particular, the autonomous vehicle 33100 b can recognize anenvironment and/or an object for an area in which the field of view isobscured and/or over a certain distance by receiving sensor informationfrom external devices, and/or receive the recognized informationdirectly from external devices.

The autonomous vehicle 33100 b can perform the above-describedoperations using a learning model composed of at least one ANN. Forexample, the autonomous vehicle 33100 b can recognize the surroundingenvironment and/or the object using the learning model, and candetermine the travel route using the recognized surrounding informationand/or the object information. The learning model may be learneddirectly from the autonomous vehicle 33100 b and/or learned from anexternal device such as the AI server 33200.

The autonomous vehicle 33100 b can directly generate a result using thelearning model and perform an operation. The autonomous vehicle 33100 bmay transmit sensor information to an external device such as the AIserver 33200 and may receive the generated result and perform anoperation.

The autonomous vehicle 33100 b may determine the travel route and/or thetravel plan using at least one of the map data, the object informationdetected from the sensor information and/or the object informationacquired from the external device, and drive the autonomous vehicle33100 b according to the determined travel route and/or travel plan bycontrolling the driving unit.

The map data may include object identification information on variousobjects arranged in a space (e.g. road) in which the autonomous vehicle33100 b moves. For example, the map data may include objectidentification information on fixed objects such as street lamps, rocks,and buildings, and/or on movable objects such as vehicles andpedestrians. The object identification information may include a name, atype, a distance, and/or a position, etc.

The autonomous vehicle 33100 b can perform the operation and/or run bycontrolling the driving unit based on the control/interaction of theuser. The autonomous vehicle 33100 b may acquire the intentioninformation of the interaction due to the user's operation and/or voiceutterance, determine the response based on the acquired intentioninformation, and perform the operation.

<AI+XR>

The XR device 33100 c may be implemented as a HMD, a HUD, a TV, a mobilephone, a smartphone, a computer, a wearable device, a home appliance, adigital signage, a vehicle, a fixed robot, a mobile robot, etc., towhich AI technology is applied.

The XR device 33100 c analyzes the three-dimensional point cloud dataand/or image data acquired from various sensors and/or from an externaldevice to generate position data and/or attribute data for thethree-dimensional points, thereby obtaining information about thesurrounding space and/or the real object, and outputting the rendered XRobject. For example, the XR device 33100 c may output an XR object,which includes the additional information about the recognized object,by corresponding to the recognized object.

The XR device 33100 c can perform the above-described operations using alearning model composed of at least one ANN. For example, the XR device33100 c can recognize a real object from three-dimensional point clouddata and/or image data using the learning model, and can provideinformation corresponding to the recognized real object. The learningmodel may be learned directly from the XR device 33100 c and/or learnedfrom an external device such as the AI server 33200.

The XR device 33100 c can directly generate a result using the learningmodel and perform an operation. The XR device 33100 c may transmitsensor information to an external device such as the AI server 33200 andmay receive the generated result and perform an operation.

<AI+Robot+Autonomous-Driving/Self-Driving>

The robot 33100 a may be implemented as a guide robot, a carrying robot,a cleaning robot, a wearable robot, an entertainment robot, a pet robot,an unmanned flying robot, etc., to which AI technology andautonomous-driving technology are applied.

The robot 33100 a to which the AI technology and the autonomous-drivingtechnology are applied may mean the robot 33100 a having theautonomous-driving function itself and/or the robot 33100 a interactingwith the autonomous vehicle 33100 b.

The robot 33100 a having an autonomous-driving function can collectivelyrefer to devices that move by themselves in accordance with a giventravel route and/or move by determining the traveling route bythemselves without user's control.

The robot 33100 a having the autonomous-driving function and theautonomous vehicle 33100 b can use a common sensing method to determineat least one of the travel route and/or the travel plan. For example,the robot 33100 a having the autonomous-driving function and theautonomous vehicle 33100 b can determine at least one of the travelroute and/or the travel plan using the information sensed through theLIDAR, the radar, and/or the camera.

The robot 33100 a interacting with the autonomous vehicle 33100 b mayexist separately from the autonomous vehicle 33100 b. The robot 33100 ainteracting with the autonomous vehicle 33100 b may be associated withthe autonomous-driving function inside and/or outside the autonomousvehicle 33100 b, and/or may perform an operation associated with theuser aboard the autonomous vehicle 33100 b.

The robot 33100 a interacting with the autonomous vehicle 33100 b mayacquire the sensor information on behalf of the autonomous vehicle 33100b and provide it to the autonomous vehicle 33100 b. The robot 33100 ainteracting with the autonomous vehicle 33100 b may obtain the sensorinformation and generate the environment information and/or the objectinformation to provide the autonomous vehicle 33100 b, therebycontrolling and/or assisting the autonomous-driving function of theautonomous vehicle 33100 b.

The robot 33100 a interacting with the autonomous vehicle 33100 b maymonitor the user boarding the autonomous vehicle 33100 b and/or maycontrol the functions of the autonomous vehicle 33100 b throughinteraction with the user. For example, when it is determined that thedriver is in a drowsy state, the robot 33100 a may activate theautonomous-driving function of the autonomous vehicle 33100 b and/orassist the control of the driving unit of the autonomous vehicle 33100b. The function of the autonomous vehicle 33100 b controlled by therobot 33100 a may include not only an autonomous-driving function butalso a function provided by a navigation system and/or an audio systemprovided in the autonomous vehicle 33100 b.

The robot 33100 a interacting with the autonomous vehicle 33100 b mayprovide information and/or assist the function to the autonomous vehicle33100 b outside the autonomous vehicle 33100 b. For example, the robot33100 a, such as a smart traffic light, may provide traffic informationincluding signal information, etc., to the autonomous vehicle 33100 b.The robot 33100 a, such as an automatic electric charger of an electricvehicle, may interact with the autonomous vehicle 33100 b to connect theelectric charger to the charging hole automatically.

<AI+Robot+XR>

The robot 33100 a may be implemented as a guide robot, a carrying robot,a cleaning robot, a wearable robot, an entertainment robot, a pet robot,an unmanned flying robot, a drone, etc., to which AI technology and XRtechnology are applied.

The robot 33100 a to which the XR technology is applied may refer to arobot that is subject to control/interaction in the XR image. In thiscase, the robot 33100 a may be separated from the XR device 33100 c andcan be associated with each other.

When the robot 33100 a that is the subject to control/interaction in theXR image acquires the sensor information from the sensors including thecamera, the robot 33100 a and/or the XR device 33100 c may generate anXR image based on the sensor information and the XR device 33100 c canoutput the generated XR image. The robot 33100 a can operate based on acontrol signal and/or a user's interaction input through the XR device33100 c.

For example, the user can acknowledge the XR image corresponding to theviewpoint of the robot 33100 a remotely linked through the externaldevice such as the XR device 33100 c, and can adjust the autonomoustravel path of the robot 33100 a, control operation and/or driving, orcheck the information of neighboring objects, through interaction.

<AI+Autonomous-Driving/Self-Driving+XR>

The autonomous vehicle 33100 b may be implemented as a mobile robot, avehicle, an unmanned aerial vehicle, etc., to which AI technology and XRtechnology are applied.

The autonomous driving vehicle 33100 b to which the XR technology isapplied may mean an autonomous vehicle having means for providing an XRimage and/or an autonomous vehicle that is subject tocontrol/interaction in the XR image. Particularly, the autonomousvehicle 33100 b that is subject to control/interaction in the XR imagemay be separated from the XR device 33100 c and can be associated witheach other.

The autonomous vehicle 33100 b having the means for providing the XRimage can acquire the sensor information from the sensors including thecamera and output the generated XR image based on the acquired sensorinformation. For example, the autonomous vehicle 33100 b may include anHUD to output an XR image, thereby providing a passenger with a realobject and/or an XR object corresponding to an object in the screen.

At this time, when the XR object is output to the HUD, at least a partof the XR object may be output so as to overlap with the actual objectthat the passenger's gaze is directed to. On the other hand, when the XRobject is output to the display provided in the autonomous vehicle 33100b, at least a part of the XR object may be output so as to overlap withthe object in the screen. For example, the autonomous vehicle 33100 bcan output XR objects corresponding to objects such as a lane, anothervehicle, a traffic light, a traffic sign, a two-wheeled vehicle, apedestrian, a building, etc.

When the autonomous vehicle 33100 b that is the subject tocontrol/interaction in the XR image acquires the sensor information fromthe sensors including the camera, the autonomous vehicle 33100 b and/orthe XR device 33100 c may generate an XR image based on the sensorinformation and the XR device 33100 c can output the generated XR image.The autonomous vehicle 33100 b can operate based on a control signaland/or a user's interaction input through the XR device 33100 c.

What is claimed is:
 1. A method for transmitting a synchronizationsignal block (SSB) in a wireless communication system, the methodperformed by a node and comprising: receiving a plurality of SSBtransmission configurations (STCs) determined by a donor node, whereineach of the plurality of STCs informs a periodicity and an offset for arelated SSB, and transmitting the related SSB based on the plurality ofSTCs, wherein the related SSB is used for discovery and measurementrelated to a child node of the node.
 2. The method of claim 1, whereinthe node receives the plurality of STCs from a parent node of the node.3. The method of claim 1, wherein at least one of the periodicity andthe offset of the related SSB is different per the plurality of STCs. 4.The method of claim 3, wherein the at least one of the periodicity andthe offset is different according to a different target node.
 5. Themethod of claim 1, wherein the node receives discovery requestinformation, and wherein the node transmits the related SSB based on thediscovery request information.
 6. The method of claim 5, wherein thediscovery request information is cell-specific or group-specific.
 7. Themethod of claim 1, wherein the related SSB includes an identifier (ID)of the node.
 8. The method of claim 1, wherein the plurality of STCs istransmitted through system information or a radio resource control (RRC)message.
 9. The method of claim 1, wherein the at least one related SSBis transmitted based on time division multiplexing (TDM) manner orfrequency division multiplexing (FDM) manner.
 10. The method of claim 1,wherein the child node is a user equipment (UE) or another node.
 11. Themethod of claim 1, wherein each of the plurality of STCs includes anindex for the related SSB, and wherein the index identifies a beamdirection for the related SSB.
 12. The method of claim 11, wherein thenode transmits the related SSB based on the beam direction.
 13. Themethod of claim 1, wherein the node is a node on integrated accessbackhaul links (IAB) system.
 14. A node, comprising: a transceivertransmitting and receiving radio signals; and a processor beingoperatively connected to the transceiver, wherein the processor isconfigured to: receive a plurality of SSB transmission configurations(STCs) determined by a donor node, wherein each of the plurality of STCsinforms a periodicity and an offset for a related SSB, and transmit therelated SSB based on the plurality of STCs, wherein the related SSB isused for discovery and measurement related to a child node of the node.